Method for configuring bandwidth for supporting broadband carrier in communication system

ABSTRACT

Disclosed is a method for configuring a bandwidth for supporting a broadband carrier in a communication system. An operation method of a base station comprises the steps of: configuring a first bandwidth part and a second bandwidth part for a terminal; configuring a reserved resource for the first bandwidth part in a resource area in which the first bandwidth part and the second bandwidth part overlap; and performing an operation of transmitting or receiving a second data channel, which is scheduled to the second bandwidth part, together with the terminal by using the reserved resource. Therefore, the performance of the communication system can be improved.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/748,162, filed on May 19, 2022, which is a continuation of U.S.application Ser. No. 16/620,809, having 371(c) date of Jun. 26, 2020(issued on Jun. 21, 2022 as U.S. Pat. No. 11,368,275), which was aNational Stage application of PCT/KR2018/006712, filed on Jun. 14, 2018,and claims priority to and the benefit of Korean Patent Applications No.10-2017-0076915, filed on Jun. 16, 2017, No. 10-2017-0083762, filed onJun. 30, 2017, No. 10-2017-0105744, filed on Aug. 21, 2017, No.10-2018-0007112, filed on Jan. 19, 2018, No. 10-2018-0013634, filed onFeb. 2, 2018, and No. 10-2018-0018709, filed on Feb. 14, 2018, theentire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a technique for configuring a bandwidthpart in a communication system, and more particularly, to a techniquefor configuring a bandwidth part to support initial access in a widebandcarrier.

BACKGROUND ART

A communication system (e.g., a new radio (NR)) using a higher frequencyband (e.g., a frequency band of 6 GHz or higher) than a frequency band(e.g., a frequency band of 6 GHz or lower) of a long term evolution(LTE) based communication system (or, a LTE-A based communicationsystem) is being considered for processing of soaring wireless data. TheNR can support not only a frequency band above 6 GHz but also afrequency band below 6 GHz, and can support various communicationservices and scenarios compared to the LTE. Further, the requirements ofthe NR may include enhanced mobile broadband (eMBB), ultra reliable lowlatency communication (URLLC), massive machine type communication(mMTC), and the like.

Meanwhile, one or more bandwidth parts may be configured in a widebandcarrier in the NR. However, a method for configuring a bandwidth partsupporting initial access in the wideband carrier, an initial accessprocedure in the configured bandwidth part, and the like are not clearlydefined. Also, when a plurality of bandwidth parts are configured in aterminal, and there is an overlapped resource region between theplurality of bandwidth parts, it is not clearly defined which associatedchannel and signal are transmitted through which bandwidth part in theoverlapped resource region. Therefore, operations of a base station anda terminal need to be clearly defined in the bandwidth part.

DISCLOSURE Technical Problem

The objective of the present invention to solve the above-describedproblem is to provide a method of configuring a bandwidth part of aterminal for supporting an initial access in a communication system.

Technical Solution

An operation method of a base station in a communication system,according to a first embodiment of the present invention for achievingthe above-described objective, may comprise configuring a firstbandwidth part and a second bandwidth part for a terminal; configuringreserved resources for the first bandwidth part in a resource regionoverlapped between the first bandwidth part and the second bandwidthpart; and performing a transceiving operation of a second data channelscheduled in the second bandwidth part with the terminal using thereserved resources.

Here, the operation method may further comprise performing atransceiving operation of a first data channel scheduled in the firstbandwidth part with the terminal using a time-frequency resourceexcluding the reserved resources in the first bandwidth part.

Here, the first data channel may be rate-matched around the reservedresources.

Here, both the first bandwidth part and the second bandwidth part may beactivated.

Here, the first bandwidth part and the second bandwidth part may belongto the same carrier configured in the terminal.

Here, each of the first bandwidth part and the second bandwidth part maybelong to a different carrier configured in the terminal.

Here, the reserved resources may be configured in the first bandwidthpart according to a numerology of the first bandwidth part.

Here, the configuration information of the reserved resources may betransmitted to the terminal through a higher layer signaling procedureor a physical layer signaling procedure.

Here, the first bandwidth part and the second bandwidth part may bedownlink bandwidth parts, and the second data channel may be a physicaldownlink shared channel (PDSCH).

An operation method of a terminal in a communication system, accordingto a second embodiment of the present invention for achieving theabove-described objective, may comprise receiving configurationinformation of a first bandwidth part and configuration information of asecond bandwidth part from a base station; receiving configurationinformation of reserved resources for the first bandwidth part in aresource region overlapped between the first bandwidth part and thesecond bandwidth part; and performing a transceiving operation of asecond data channel scheduled in the second bandwidth part with the basestation using the reserved resources.

Here, the operation method may further comprise performing atransceiving operation of a first data channel scheduled in the firstbandwidth part with the base station using a time-frequency resourceexcluding the reserved resources in the first bandwidth part.

Here, the first data channel may be rate-matched around the reservedresources.

Here, both the first bandwidth part and the second bandwidth part may beactivated.

Here, the first bandwidth part and the second bandwidth part may belongto the same carrier configured in the terminal.

Here, each of the first bandwidth part and the second bandwidth part maybelong to a different carrier configured in the terminal.

Here, the reserved resources may be configured in the first bandwidthpart according to a numerology of the first bandwidth part.

Here, the configuration information of the reserved resources may bereceived from the base station through a higher layer signalingprocedure or a physical layer signaling procedure.

Here, the first bandwidth part and the second bandwidth part may bedownlink bandwidth parts, and the second data channel may be a physicaldownlink shared channel (PDSCH).

An operation method of a terminal in a communication system, accordingto a third embodiment of the present invention for achieving theabove-described objective, may comprise receiving configurationinformation indicating a semi-static slot format from a base station;identifying a reference subcarrier spacing of the semi-static slotformat based on the configuration information; and determining that asubcarrier spacing of a bandwidth part of the terminal is greater thanor equal to the reference subcarrier spacing.

Here, the method may further comprise configuring a type of a firstsymbol in the bandwidth part to be equal to a type of a second symbol inaccordance with the semi-static slot format located at a same time pointas the first symbol.

Advantageous Effects

In accordance with the present invention, a plurality of bandwidth parts(e.g., a first bandwidth part, a second bandwidth part) may beconfigured in a terminal, and reserved resources for the first bandwidthpart may be configured in an overlapped resource region between thefirst bandwidth part and the second bandwidth part. The enhanced mobilebroadband (eMBB) data can be transmitted or received through atime-frequency resource other than the reserved resources in theoverlapped resource region within the first bandwidth part, and theultra-reliable low-latency communication (URLLC) data can be transmittedor received through the reserved resources. That is, when the reservedresources are configured, high-reliability and low-latency requirementsin the NR can be satisfied.

In addition, when a semi-static slot format is used, a referencesubcarrier spacing of the semi-static slot format may be set to thesmallest subcarrier spacing candidate among subcarrier spacingcandidates available for the bandwidth part. In this case, a problemthat one symbol of the bandwidth part is mapped to symbols havingdifferent transmission directions according to the semi-static slotformat can be solved. Alternatively, when the reference subcarrierspacing of the semi-static slot format is greater than the subcarrierspacing of the bandwidth part, one symbol of the bandwidth part may bemapped to symbols having different transmission directions according tothe semi-static slot format. In this case, the transmission direction ofthe one symbol of the bandwidth part may be determined according to apredetermined rule. Therefore, the performance of the communicationsystem can be improved.

DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram illustrating a first embodiment of acommunication system.

FIG. 2 is a block diagram illustrating a first embodiment of acommunication node constituting a communication system.

FIG. 3 is a conceptual diagram illustrating a first embodiment of areserved resource configuration method according to Method 300 in acommunication system.

FIG. 4 is a conceptual diagram illustrating a first embodiment of asemi-static slot format in a communication system.

FIG. 5 is a conceptual diagram illustrating a second embodiment of asemi-static slot format in a communication system.

FIG. 6 is a conceptual diagram illustrating a first embodiment ofconfiguration of a semi-static slot format and a bandwidth part in acommunication system.

FIG. 7 is a conceptual diagram illustrating a second embodiment ofconfiguration of a semi-static slot format and a bandwidth part in acommunication system.

FIG. 8 is a conceptual diagram illustrating a first embodiment of a slotformat of a bandwidth part according to Method 411 in a communicationsystem.

FIG. 9A is a conceptual diagram illustrating a first embodiment of asemi-static slot format according to Method 421.

FIG. 9B is a conceptual diagram illustrating a second embodiment of asemi-static slot format according to Method 421.

FIG. 9C is a conceptual diagram illustrating a third embodiment of asemi-static slot format according to Method 421.

FIG. 10 is a conceptual diagram illustrating a first embodiment of adynamic switching method of a bandwidth part in a communication system.

FIG. 11A is a conceptual diagram illustrating a first embodiment of anRF transition duration in a communication system.

FIG. 11B is a conceptual diagram illustrating a second embodiment of anRF transition duration in a communication system.

FIG. 11C is a conceptual diagram illustrating a third embodiment of anRF transition duration in a communication system.

FIG. 12 is a conceptual diagram illustrating a first embodiment of anSFI monitoring occasion in a communication system.

FIG. 13 is a conceptual diagram illustrating a second embodiment of anSFI monitoring occasion in a communication system.

FIG. 14 is a conceptual diagram illustrating a first embodiment of a PImonitoring occasion in a communication system.

MODES OF THE INVENTION

While the present invention is susceptible to various modifications andalternative forms, specific embodiments are shown by way of example inthe drawings and described in detail. It should be understood, however,that the description is not intended to limit the present invention tothe specific embodiments, but, on the contrary, the present invention isto cover all modifications, equivalents, and alternatives that fallwithin the spirit and scope of the present invention.

Although the terms “first,” “second,” etc. may be used herein inreference to various elements, such elements should not be construed aslimited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and a second element could be termed a first element,without departing from the scope of the present invention. The term“and/or” includes any and all combinations of one or more of theassociated listed items.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directed coupled” to another element, there are nointervening elements.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of embodiments ofthe present invention. As used herein, the singular forms “a,” “an,” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will be further understood thatthe terms “comprises,” “comprising,” “includes,” and/or “including,”when used herein, specify the presence of stated features, integers,steps, operations, elements, parts, and/or combinations thereof, but donot preclude the presence or addition of one or more other features,integers, steps, operations, elements, parts, and/or combinationsthereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by thoseof ordinary skill in the art to which the present invention pertains. Itwill be further understood that terms defined in commonly useddictionaries should be interpreted as having a meaning that isconsistent with their meaning in the context of the related art and willnot be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Hereinafter, exemplary embodiments of the present invention will bedescribed in greater detail with reference to the accompanying drawings.To facilitate overall understanding of the present invention, likenumbers refer to like elements throughout the description of thedrawings, and description of the same component will not be reiterated.

The communication systems to which embodiments according to the presentinvention are applied will be described. The communication system may bea 4G communication system (e.g., a long-term evolution (LTE)communication system, an LTE-A communication system), a 5G communicationsystem (e.g. a new radio (NR) communication system), or the like. The 4Gcommunication system can support communication in a frequency band of 6GHz or less, and the 5G communication system can support communicationin a frequency band of 6 GHz or less as well as a frequency band of 6GHz or more. The communication system to which the embodiments accordingto the present invention are applied is not limited to the followingdescription, and the embodiments according to the present invention canbe applied to various communication systems. Here, the communicationsystem may be used in the same sense as a communication network, ‘LTE’may indicate the ‘4G communication system’, the ‘LTE communicationsystem’, or the ‘LTE-A communication system’, and ‘NR’ may indicate the‘5G communication system’ or the ‘NR communication system’.

FIG. 1 is a conceptual diagram illustrating a first embodiment of acommunication system.

Referring to FIG. 1 , a communication system 100 may comprise aplurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2,130-1, 130-2, 130-3, 130-4, 130-5, and 130-6. Also, the communicationsystem 100 may comprise a core network (e.g., a serving gateway (S-GW),a packet data network (PDN) gateway (P-GW), a mobility management entity(MME), and the like). When the communication system 100 is a 5Gcommunication system (e.g., a new radio (NR) system), the core networkmay include an access and mobility management function (AMF), a userplane function (UPF), a session management function (SMF), and the like.

The plurality of communication nodes 110 to 130 may support acommunication protocol (e.g., long term evolution (LTE) communicationprotocol, LTE-advanced (LTE-A) communication protocol, NR communicationprotocol) defined in the 3rd generation partnership project (3GPP)standard. The plurality of communication nodes 110 to 130 may support atleast one communication protocol among a code division multiple access(CDMA) technology, a wideband CDMA (WCDMA) technology, a time divisionmultiple access (TDMA) technology, a frequency division multiple access(FDMA) technology, an orthogonal frequency division multiplexing (OFDM)technology, a filtered OFDM technology, a cyclic prefix (CP)-OFDMtechnology, a discrete Fourier transform-spread-OFDM (DFT-s-OFDM)technology, an orthogonal frequency division multiple access (OFDMA)technology, a single carrier FDMA (SC-FDMA) technology, a non-orthogonalmultiple access (NOMA) technology, a generalized frequency divisionmultiplexing (GFDM) technology, a filter band multi-carrier (FBMC)technology, an universal filtered multi-carrier (UFMC) technology, aspace division multiple access (SDMA) technology, and the like. Each ofthe plurality of communication nodes may have the following structure.

FIG. 2 is a block diagram illustrating a first embodiment of acommunication node constituting a communication system.

Referring to FIG. 2 , a communication node 200 may comprise at least oneprocessor 210, a memory 220, and a transceiver 230 connected to thenetwork for performing communications. Also, the communication node 200may further comprise an input interface device 240, an output interfacedevice 250, a storage device 260, and the like. Each component includedin the communication node 200 may communicate with each other asconnected through a bus 270.

The processor 210 may execute a program stored in at least one of thememory 220 and the storage device 260. The processor 210 may refer to acentral processing unit (CPU), a graphics processing unit (GPU), or adedicated processor on which methods in accordance with embodiments ofthe present disclosure are performed. Each of the memory 220 and thestorage device 260 may be constituted by at least one of a volatilestorage medium and a non-volatile storage medium. For example, thememory 220 may comprise at least one of read-only memory (ROM) andrandom access memory (RAM).

Referring again to FIG. 1 , the communication system 100 may comprise aplurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2, and aplurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6. Thecommunication system 100 comprising the base stations 110-1, 110-2,110-3, 120-1, and 120-2 and the terminals 130-1, 130-2, 130-3, 130-4,130-5, and 130-6 may be referred to as an ‘access network’. Each of thefirst base station 110-1, the second base station 110-2, and the thirdbase station 110-3 may form a macro cell, and each of the fourth basestation 120-1 and the fifth base station 120-2 may form a small cell.The fourth base station 120-1, the third terminal 130-3, and the fourthterminal 130-4 may belong to cell coverage of the first base station110-1. Also, the second terminal 130-2, the fourth terminal 130-4, andthe fifth terminal 130-5 may belong to cell coverage of the second basestation 110-2. Also, the fifth base station 120-2, the fourth terminal130-4, the fifth terminal 130-5, and the sixth terminal 130-6 may belongto cell coverage of the third base station 110-3. Also, the firstterminal 130-1 may belong to cell coverage of the fourth base station120-1, and the sixth terminal 130-6 may belong to cell coverage of thefifth base station 120-2.

Here, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1,and 120-2 may be referred to as a Node B (NodeB), an evolved Node B(eNodeB), a gNB, an advanced base station (ABS), a high reliability-basestation (HR-BS), a base transceiver station (BTS), a radio base station,a radio transceiver, an access point (AP)), an access node, a radioaccess station (RAS), a mobile multihop relay-base station (MMR-BS), arelay station (RS), an advanced relay station (ARS), a highreliability-relay station (HR-RS), a home NodeB (HNB), a home eNodeB(HeNB), a road side unit (RSU), a radio remote head (RRH), atransmission point (TP), a transmission and reception point (TRP), orthe like.

Each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5,and 130-6 may be referred to as a user equipment (UE), a terminalequipment (TE), an advanced mobile station (AMS), a highreliability-mobile station (HR-MS), a terminal, an access terminal, amobile terminal, a station, a subscriber station, a mobile station, aportable subscriber station, a node, a device, a mounted module, an onboard unit (OBU), or the like.

Meanwhile, each of the plurality of base stations 110-1, 110-2, 110-3,120-1, and 120-2 may operate in the same frequency band or in differentfrequency bands. The plurality of base stations 110-1, 110-2, 110-3,120-1, and 120-2 may be connected to each other via an ideal backhaul ora non-ideal backhaul, and exchange information with each other via theideal or non-ideal backhaul. Also, each of the plurality of basestations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to thecore network through the ideal or non-ideal backhaul. Each of theplurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 maytransmit a signal received from the core network to the correspondingterminal 130-1, 130-2, 130-3, 130-4, 130-5, or 130-6, and transmit asignal received from the corresponding terminal 130-1, 130-2, 130-3,130-4, 130-5, or 130-6 to the core network.

Also, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1,and 120-2 may support a multi-input multi-output (MIMO) transmission(e.g., a single-user MIMO (SU-MIMO), a multi-user MIMO (MU-MIMO), amassive MIMO, or the like), a coordinated multipoint (CoMP)transmission, a carrier aggregation (CA) transmission, a transmission inunlicensed band, a device-to-device (D2D) communications (or, proximityservices (ProSe)), or the like. Here, each of the plurality of terminals130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 may perform operationscorresponding to the operations of the plurality of base stations 110-1,110-2, 110-3, 120-1, and 120-2 (i.e., the operations supported by theplurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2). Forexample, the second base station 110-2 may transmit a signal to thefourth terminal 130-4 in the SU-MIMO manner, and the fourth terminal130-4 may receive the signal from the second base station 110-2 in theSU-MIMO manner. Alternatively, the second base station 110-2 maytransmit a signal to the fourth terminal 130-4 and fifth terminal 130-5in the MU-MIMO manner, and the fourth terminal 130-4 and fifth terminal130-5 may receive the signal from the second base station 110-2 in theMU-MIMO manner.

Each of the first base station 110-1, the second base station 110-2, andthe third base station 110-3 may transmit a signal to the fourthterminal 130-4 in the CoMP transmission manner, and the fourth terminal130-4 may receive the signal from the first base station 110-1, thesecond base station 110-2, and the third base station 110-3 in the CoMPmanner. Also, each of the plurality of base stations 110-1, 110-2,110-3, 120-1, and 120-2 may exchange signals with the correspondingterminals 130-1, 130-2, 130-3, 130-4, 130-5, or 130-6 which belongs toits cell coverage in the CA manner. Each of the base stations 110-1,110-2, and 110-3 may control D2D communications between the fourthterminal 130-4 and the fifth terminal 130-5, and thus the fourthterminal 130-4 and the fifth terminal 130-5 may perform the D2Dcommunications under control of the second base station 110-2 and thethird base station 110-3.

Meanwhile, in order to efficiently use a wide frequency band in acommunication system, a system bandwidth supported by the NR may bewider than a system bandwidth supported by the LTE. For example, themaximum system bandwidth supported by the LTE may be 20 MHz, and themaximum system bandwidth supported by the NR may be 400 MHz. Also, theminimum system bandwidth supported by the LTE may be 1.4 MHz. On theother hand, the minimum system bandwidth supported by the NR in thefrequency band below 6 GHz may be 5 MHz, and the minimum systembandwidth supported by the NR in the frequency band above 6 GHz may be50 MHz.

Unlike the LTE, the NR may support various bandwidth capabilities ofterminal. In the LTE, a normal terminal excluding a machine typecommunication (MTC) terminal can support the maximum system bandwidth of20 MHz. On the other hand, the maximum system bandwidth of 400 MHz inthe NR can be supported by some terminals. For example, the maximumsystem bandwidth that can be supported by a specific terminal may be 20MHz, and the maximum system bandwidth that can be supported by otherterminals may be 100 MHz. However, the minimum system bandwidth in theNR may be defined commonly in all terminals. For example, the minimumsystem bandwidth of the NR applied to all terminals in the frequencyband below 6 GHz may be 20 MHz. The bandwidth capability may be definedaccording to the system bandwidth. Alternatively, the bandwidthcapability may be defined according to factors (e.g., fast Fouriertransform (FFT) size, number of subcarriers, etc.) other than the systembandwidth.

Therefore, terminals with various bandwidth capabilities may operate inthe same wideband carrier. In this case, a terminal with a bandwidthcapability that can operate in an entire bandwidth (e.g., systembandwidth) of a wideband carrier by a single carrier operation withoutcarrier aggregation may be referred to as a ‘wideband terminal’. Aterminal with a bandwidth capability that can operate only in a partialbandwidth of a wideband carrier by a single carrier operation may bereferred to as a ‘narrowband terminal’. Further, when a partialfrequency region of a wideband carrier is used as an independentcarrier, the independent carrier may be referred to as a ‘narrowbandcarrier’, which is relative to the wideband carrier.

For example, a carrier with a system bandwidth of 100 MHz may bepresent, and 5 carriers with a system bandwidth of 20 MHz within thebandwidth of 100 MHz may exist without overlapping system bandwidth. Inthis case, the carrier having the system bandwidth of 100 MHz may bereferred to as the ‘wideband carrier’, and the carrier having the systembandwidth of 20 MHz may be referred to as the ‘narrowband carrier’.Also, since the narrowband carrier is a partial frequency region withinthe wideband carrier, the narrow band carrier may be referred to as a‘wideband-sub carrier’.

In order to support both the wideband terminal and the narrowbandterminal in a wideband carrier, a bandwidth part may be used. Thebandwidth part may be defined as a set of consecutive physical resourceblocks (PRBs) in the frequency domain, and at least one numerology(e.g., subcarrier spacing and cyclic prefix (CP) length) may be used fortransmission of control channels or data channels within a bandwidthpart.

The base station may configure one or more terminal-specific(UE-specific) bandwidth parts, and may inform a terminal ofconfiguration information of the one or more UE-specific bandwidth partsthrough a signaling procedure. In the following embodiments, thesignaling procedure may mean at least one of a higher layer signalingprocedure (e.g., a radio resource control (RRC) signaling procedure) anda physical layer signaling procedure (e.g., a downlink controlinformation (DCI) signaling procedure). The terminal may performtransmission and reception of a data channel (e.g., physical downlinkshared channel (PDSCH) reception or physical uplink shared channel(PUSCH) transmission) by using a PRB or a resource block group (RBG) inthe bandwidth part configured by the base station as a resourceallocation unit of the frequency domain.

The RBG may be used for a bitmap-based frequency domain resourceallocation scheme (e.g., type 0 resource allocation scheme of the NR),and whether or not a resource is allocated for each RBG may be indicatedthrough each bit of the bitmap. One RBG may be composed of one or morePRBs consecutive in the frequency domain, and the number of PRBs per RBGmay be predefined in the specification. Alternatively, the base stationmay inform the terminal of the number of PRBs per RBG through asignaling procedure. One transport block (TB) may be transmitted withinone bandwidth part. Alternatively, one TB may be allowed to betransmitted through a plurality of bandwidth parts.

The configuration information of the bandwidth part may be transmittedfrom the base station to the terminal through a signaling procedure. Theconfiguration information of the bandwidth part may include a numerology(e.g., subcarrier spacing, CP length, etc.) of the bandwidth part, alocation of the starting PRB of the bandwidth part, the number of PRBsof the bandwidth part, and the like. The location of the starting PRBmay be represented by an RB index in a common RB grid. A maximum of 4bandwidth parts for each of uplink and downlink may be configured for aterminal in one carrier. In a time division duplex (TDD) basedcommunication system, a pair of bandwidth parts for uplink and downlinkmay be configured.

At least one bandwidth part of the bandwidth part(s) configured in theterminal may be activated. For example, one uplink bandwidth part andone downlink bandwidth part may be activated in one carrier. In theTDD-based communication system, a pair of bandwidth parts for uplink anddownlink may be activated.

When a plurality of bandwidth parts are configured in one carrier, theactive bandwidth part may be switched. For example, a deactivationoperation of the existing active bandwidth part and an activationoperation of a new bandwidth part may be performed. In a frequencydivision duplex (FDD) based communication system, a bandwidth partswitching method may be applied to each of uplink and downlink, and in aTDD based communication system, a pair of bandwidth parts for uplink anddownlink may be switched. The switching of the active bandwidth part maybe performed by a higher layer signaling procedure (e.g., RRC signalingprocedure).

Alternatively, the switching of the active bandwidth part may beperformed dynamically by a physical layer signaling procedure (e.g., DCIsignaling procedure). In this case, a ‘bandwidth part indicator field’included in a DCI may indicate the index of the bandwidth part for whichactivation is requested. When the DCI is received from the base stationand the bandwidth part indicated by the bandwidth part indicator fieldincluded in the DCI is different from the current active bandwidth part,the terminal may determine that the bandwidth part indicated by the DCIis switched to a new active bandwidth part instead of the current activebandwidth part. Here, the DCI may include scheduling information of adata channel (e.g., PDSCH or PUSCH). In this case, the data channelscheduled by the DCI may be transmitted in the bandwidth part indicatedby the bandwidth part indicator field of the DCI.

Meanwhile, system information of the NR may be classified into minimumsystem information (MSI) and other system information (OSI). Some MSIs(e.g., master information block (MIB)) among the MSIs may be transmittedvia a physical broadcast channel (PBCH), and the remaining MSIs (e.g.,SIB-1, SIB-2, or the like) may be transmitted via PDSCH. In theembodiments described below, the some MSIs (e.g., MIB) may be referredto as the ‘PBCH’.

The PDSCH through which the remaining MSI (RMSI) is transmitted may bescheduled by a physical downlink control channel (PDCCH) (e.g., DCIincluded in the PDCCH), and a cyclic redundancy check (CRC) scrambledwith a system information-radio network temporary identifier (SI-RNTI)may be applied to the PDCCH. In the following embodiments, scheduling ofthe PDSCH by the PDCCH may mean that the DCI including the schedulinginformation of the PDSCH is transmitted through the PDCCH. The PBCH(e.g., MIB), RMSI, and OSI may be broadcast in the entire cell coverageof the base station. In a beamforming based communication system (e.g.,a communication system that supports a millimeter wave band), the PBCH(e.g., MIB), RMSI, and OSI may be transmitted in the entire cellcoverage of the base station based on a beam sweeping scheme.

In the NR, a synchronization signal (SS)/PBCH block may be composed of aprimary synchronization signal (PSS), a secondary synchronization signal(SSS), and a PBCH. The SS/PBCH block may also include a demodulationreference signal (DMRS) for demodulating the PBCH. One SS/PBCH block mayinclude one PSS (or, one PSS resource), one SSS (or, one SSS resource),and one PBCH (or, one PBCH resource), and one SS burst set (e.g., oneinterval of an SS burst set) may comprise a plurality of SS/PBCH blocks.For example, in a frequency band below 3 GHz, an SS burst set maycomprise up to 4 SS/PBCH blocks, and in a frequency band from 3 to 6GHz, an SS burst set may comprise up to 8 SS/PBCH blocks. In a frequencyband above 6 GHz, an SS burst set may comprise up to 64 SS/PBCH blocks.A candidate resource location in which the SS/PBCH block can betransmitted may be defined in the specification, and the base stationmay transmit the SS/PBCH block at the candidate resource locationdefined in the specification. Alternatively, the base station may nottransmit the SS/PBCH block at the candidate resource location defined inthe specification.

In the NR, a random access procedure may be composed of 4 steps. In thefirst step, a terminal attempting to establish an RRC connection maytransmit a physical random access channel (PRACH) (e.g., message 1(Msg1), random access preamble) to a base station in a preconfiguredresource region. In the second step, the base station receiving thePRACH may transmit a random access response (RAR) message (e.g., Msg2),which is a response to the PRACH, to the terminal within a predeterminedtime (e.g., RAR window). The RAR message may be transmitted through thePDSCH, and the PDSCH including the RAR message may be scheduled by thePDCCH.

In the third step, the terminal receiving the RAR message may transmitMsg3 to the base station in an uplink resource region (e.g., PUSCH)indicated by the RAR message. Msg3 may include an RRC connection requestmessage. In the fourth step, the base station receiving Msg3 maytransmit Msg4 to the terminal to resolve a collision caused bysimultaneous accesses of a plurality of terminals. Msg4 may betransmitted through a PDSCH, and the PDSCH including Msg4 may bescheduled by the PDCCH.

The minimum unit of resources constituting the PDCCH in the NR may be aresource element group (REG). The REG may be composed of one PRB (e.g.,12 subcarriers) in the frequency domain and one symbol (e.g., OFDMsymbol) in the time domain. Thus, one REG may include 12 resourceelements (REs). Within one REG, some REs may be used for transmission ofthe DMRS for demodulation of the PDCCH. One PDCCH candidate may becomposed of one control channel element (CCE) or aggregated CCEs, andone CCE may be composed of a plurality of REGs (e.g., 6 REGs).

A control resource set (CORESET) may be a resource region on which theterminal performs blind decoding of the PDCCH. The control resource setmay be composed of a plurality of REGs. The control resource set maycomprise a plurality of PRBs in the frequency domain and one or moresymbols (e.g., one or more OFDM symbols) in the time domain. The symbolsconstituting one control resource set may be continuous in the timedomain, and the PRBs constituting one control resource set may becontinuous or discontinuous in the frequency domain.

One or more control resource sets may be configured in one cell or onecarrier. Since the NR can support a single carrier having a widerbandwidth (e.g., up to 400 MHz) than the conventional communicationsystem, a plurality of control resource sets may be configured in onecarrier. Also, one or more control resource sets may be configured forone terminal. Even when a plurality of control resource sets areconfigured for one terminal, one DCI may be transmitted in one controlresource set. The location of the control resource set in the timedomain (e.g., period during which the terminal monitors the controlresource set) may be configured by the base station, and the basestation may inform the terminal of the location of the control resourceset in the time domain. The location of the control resource set in thetime domain may be configured in various units (e.g., in unit ofslot(s), in unit of symbol(s)).

The terminal may use a blind decoding scheme based on CRC to receive aPDCCH. A DCI transmitted through the PDCCH may include a common DCIcommon to a plurality of terminals and a terminal-specific (UE-specific)DCI for a specific terminal. For example, the common DCI or a groupcommon DCI may include resource allocation information of systeminformation, paging message, power control command, slot formatindicator (SFI), preemption indication (PI), and the like. TheUE-specific DCI may include scheduling information of an uplink datachannel, scheduling information of a downlink data channel, and thelike. Also, a PDCCH search space may be classified into a common searchspace and a terminal-specific (UE-specific) search space. The common DCImay be transmitted through the common search space, and the UE-specificDCI may be transmitted through the UE-specific search space.Alternatively, the UE-specific DCI may be transmitted in the commonsearch space, considering scheduling flexibility, fallback transmission,and the like.

Meanwhile, a slot format of the NR may be composed of a combination of adownlink duration, an unknown duration, and an uplink duration. Each ofthe downlink duration, the unknown duration and the uplink duration maybe composed of one or more consecutive symbols. One slot may include 0,1, or 2 unknown durations, and the unknown duration may be disposedbetween the downlink duration and the uplink duration.

The slot format of the NR may be configured semi-statically by a higherlayer signaling. The slot format configured semi-statically may bereferred to as a ‘semi-static slot format’. The semi-static slot formatmay be configured in a cell-specific manner, and the configurationinformation of the semi-static slot format may be system information orcommon RRC information. Also, the semi-static slot format may beadditionally configured for each terminal through a UE-specific RRCsignaling. For example, the unknown duration according to the slotformat configured by the cell-specific signaling procedure may beoverridden by the UE-specific RRC signaling to be the downlink durationor the uplink duration.

Also, the slot format may be dynamically indicated by the DCI. The slotformat configured dynamically may be referred to as a ‘dynamic slotformat’. The unknown duration according to the semi-static slot formatconfiguration may be overridden by the dynamic slot format (e.g., SFI)to be the downlink duration or the uplink duration. One SFI may indicatea slot format applied to one or more consecutive slots, and the numberof slots to which one SFI is applied may be smaller than a SFImonitoring period.

Anchor Bandwidth Part

The system information (e.g., MSI, OSI, RMSI, etc.) and the pagingmessage may be broadcast to a plurality of unspecified terminals in thecell. Therefore, a common PRB set and a common numerology may be definedso that a plurality of terminals receive a PDSCH including the systeminformation or the paging message using the same DCI. The common PRB setand the common numerology may be defined as an anchor bandwidth part.

The anchor bandwidth part may be used for transmission of broadcastinformation (e.g., RMSI, OSI, paging message, etc.), and the anchorbandwidth part may be defined in downlink. In uplink, a PRACH resourceregion may be configured separately regardless of the anchor bandwidthpart. Also, the PUSCH resource region for transmitting Msg3 may beallocated in another bandwidth part instead of the anchor bandwidthpart. In the following embodiments, the anchor bandwidth part may mean abandwidth part configured in downlink.

Information on the frequency region (e.g., number of PRB s, frequencylocation, etc.) occupied by the anchor bandwidth part may be derivedfrom the frequency region of the SS/PBCH block or PBCH. Alternatively,the frequency region occupied by the anchor bandwidth part may beconfigured by the PBCH. The numerology of the anchor bandwidth part maybe configured by the PBCH. The numerology of the anchor bandwidth partmay differ from the numerology for the SS/PBCH block. For example, a 30kHz subcarrier spacing may be used for transmission of the SS/PBCHblock, and a 15 kHz subcarrier spacing may be used for transmission ofphysical channels except the SS/PBCH block within the anchor bandwidthpart. The frequency region of the SS/PBCH block used to derive orconfigure the frequency region of the anchor bandwidth part may beincluded in the frequency region of the corresponding anchor bandwidthpart.

On the other hand, in the 4-step random access procedure, the terminaltransmitting the PRACH may expect to receive Msg2 from the base station,and the terminal may receive Msg2 in the anchor bandwidth part. Forexample, the terminal may receive a DCI that schedules a PDSCH includingMsg2 through a PDCCH configured in the anchor bandwidth part (e.g.,PDCCH logically associated with the anchor bandwidth part). At thereception of Msg2, a downlink operating bandwidth of the terminal may belimited to only the anchor bandwidth part. In this case, it may benatural that the terminal receives Msg2 in the anchor bandwidth part. Ifthe downlink operating bandwidth of the terminal at the time ofreception of Msg2 is set to a different bandwidth part instead of theanchor bandwidth part, the terminal may receive Msg2 through anotherbandwidth part. However, the signaling overhead may increase because aPBCH (e.g., MSI) or RMSI including configuration information of anotherbandwidth part should be transmitted from the base station to theterminal.

The control resource set or the PDCCH common search space may beconfigured by PBCH (e.g., MSI) or RMSI. The common search spaceconfigured by the PBCH may be logically associated with the anchorbandwidth part. According to the logical association between the commonsearch space and the anchor bandwidth part, the terminal receiving theDCI in the common search space may determine that the PDSCH scheduled bythe received DCI is the PDSCH transmitted in the anchor bandwidth part.Also, the terminal may determine that a PRB index or an RBG indexindicated by the DCI is a local index defined within the anchorbandwidth part.

The DMRS used for demodulating the physical channel within the anchorbandwidth part may be generated based on the PRB s constituting theanchor bandwidth part, and may be mapped to REs. For example, when theanchor bandwidth part is composed of 24 PRBs, the mapping starting pointof the DMRS in the frequency domain may be one of the 24 PRBs. Also, thelength of the sequence of DMRS may be defined based on 24 PRBs. Forexample, when a DMRS pattern is composed of 4 REs per port in one PRB,the sequence length of the DMRS per port may be 24×4=96.

Secondary Bandwidth Part

In the fourth step of the random access procedure, the terminal mayexpect to receive Msg4 from the base station. Msg4 may be unicast datatransmitted to a specific terminal. The PDSCH including Msg4 may bescheduled by a DCI scrambled by a temporary cell-radio network temporaryidentifier (TC-RNTI) or a cell-RNTI (C-RNTI). The terminal may receivethe unicast data at a reception time point of Msg4 or after thereception time point of Msg4.

The transmission of Msg4 or unicast data may generally be scheduled bythe DCI obtained in the UE-specific search space. However, in some cases(e.g., fallback), the transmission of Msg4 or unicast data may bescheduled by the DCI obtained in the common search space. Since thetransmission of Msg4 or unicast data is scheduled by the UE-specificDCI, each of Msg4 and unicast data may not necessarily be transmitted inthe anchor bandwidth part. Also, when the TB size of the unicast data isrelatively large and the bandwidth of the anchor bandwidth part isrelatively small, the size of the TB that can be scheduled in one slotof the anchor bandwidth pert may be limited. Also, when the terminal canarbitrarily change a quasi co-location (QCL) assumption to receivebroadcast information in the anchor bandwidth part, the terminal may berequired to receive QCL-related information from the base station inorder to receive the unicast data in the anchor bandwidth part.

Therefore, a separate bandwidth part may be configured for unicasttransmission. The bandwidth part for the transmission of Msg4 or unicastdata may be configured through an initial access procedure of theterminal. The bandwidth part for the transmission of Msg4 or unicastdata may be referred to as a ‘secondary bandwidth part’. The secondarybandwidth part may be configured for downlink transmission.

Meanwhile, in the NR, in addition to the PRB grid defined in thebandwidth part, a broader concept common RB grid may be used to supportwideband operations. The common RB grid may be defined as a virtual RBgrid that is a reference within a specific frequency region regardlessof the frequency region physically occupied by a carrier or bandwidthpart. The common RB grid may be used as a basis for configuring acarrier or bandwidth part, and a location of a specific RB (e.g., firstRB or first subcarrier in the first RB) of the common RB grid may beconfigured in the terminal as an offset with a specific RB (e.g., firstRB or first subcarrier in the first RB) of an SS/PBCH block. The commonRB grid may be defined for each subcarrier spacing.

The DMRS used for demodulation of physical channels within the secondarybandwidth part may be generated based on the common RB grid, and may bemapped to REs. For example, a RB #100 of the common RB grid may be a PRB#0 of a specific bandwidth part configured in the first terminal and aPRB #50 of a specific bandwidth part configured in the second terminalsimultaneously. In this case, the DMRS may be generated based on an RBindex (i.e., RB #100) of the common RB grid regardless of a local PRBindex within the specific bandwidth part, and may be mapped to REs.

Therefore, the base station may generate a DMRS for the first terminaland a DMRS for the second terminal based on a code division multiplexing(CDM) scheme, and map the DMRS for the first terminal and the DMRS forthe second terminal to the same REs. Also, RSs (e.g., CSI-RS, SRS)transmitted within the secondary bandwidth part may be generated basedon the common RB grid and may be mapped to REs. When the secondarybandwidth part overlaps with the UE-specific bandwidth part, the sameRSs (e.g., CSI-RS, SRS) may be used in both the secondary bandwidth partand the UE-specific bandwidth part. Accordingly, the RS overhead can bereduced.

In order to quickly obtain the effect described above, it may beadvantageous that the secondary bandwidth part is configured at theearliest time point in the terminal. Accordingly, the secondarybandwidth part may be configured in the terminal by Msg2. The terminalmay obtain configuration information of the secondary bandwidth partfrom Msg2 received via the PDSCH, and configure the secondary bandwidthpart based on the obtained configuration information. The transmissionof the configuration information of the secondary bandwidth part throughMsg2 may have an advantage over transmission of the configurationinformation of the secondary bandwidth part through RMSI.

In the communication system using multiple beams, the RMSI may betransmitted several times by beam sweeping to cover the entire cell.Since Msg2 is transmitted to the terminal having transmitted Msg1, thenumber of transmissions of the configuration information of thesecondary bandwidth part may be reduced in the communication systemusing the multiple beams. For example, the base station may transmitMsg2 to the terminal having transmitted a PRACH by using the same beamas the beam used for reception of the PRACH (i.e., Msg1). According tothe method described above, up to Msg2 may be transmitted in the anchorbandwidth part, and Msg4 or unicast data may be transmitted in thesecondary bandwidth part. In this case, the configuration information ofthe secondary bandwidth part need not be transmitted at a time earlierthan Msg2.

According to the method described above, the anchor bandwidth part maybe configured or derived via the PBCH, and the secondary bandwidth partmay be configured via Msg2. Meanwhile, it may be difficult for the basestation to know the bandwidth capability of the terminal attemptinginitial access at the time of encoding Msg2. Therefore, the size of eachof the anchor bandwidth part and the secondary bandwidth part may be setto be equal to or less than a minimum bandwidth commonly supported byall the terminals. For example, when the minimum bandwidth of theterminal is 20 MHz, the size of each of the anchor bandwidth part andthe secondary bandwidth part may be set to 20 MHz or less. The secondarybandwidth part may be configured in common to a plurality of terminalsinstead of a specific terminal. For example, the configurationinformation of the secondary bandwidth portion may be cell-specific orterminal group-specific. For example, when the secondary bandwidth partis configured by Msg2, the configuration information of the samesecondary bandwidth part within one anchor bandwidth part may betransmitted. Even when Msg2 includes UE-specific information, theconfiguration information of the same secondary bandwidth part withinone anchor bandwidth portion may be transmitted.

The secondary bandwidth part may be a bandwidth part temporarily used bythe terminal attempting initial access. Since the NR supports terminalshaving various bandwidth capabilities, the terminal may transmitUE-specific data in the secondary bandwidth part until the base stationacquires bandwidth capability information of the terminal. On the otherhand, the base station may operate based on the following two methodsafter obtaining the bandwidth capability information of the terminalattempting initial access.

As a first method, a base station may inform a terminal (e.g., widebandterminal) supporting a bandwidth (e.g., 100 MHz) wider than the size ofthe secondary bandwidth part (e.g., 20 MHz) of configuration informationof a wideband carrier, and may additionally configure a new bandwidthpart for the terminal. The new bandwidth part for the terminal may beconfigured by RRC signaling and configured for each of downlink anduplink. When the new bandwidth part is configured, the terminal mayperform transmission using the new bandwidth part in the widebandcarrier. In this case, the terminal may not use the secondary bandwidthpart. For example, the terminal may not monitor the UE-specific searchspace logically associated with the secondary bandwidth part.Alternatively, the terminal may maintain the configuration of thesecondary bandwidth part, and may perform transmission using both thenew bandwidth part and the secondary bandwidth part. Alternatively, whenthe new bandwidth part is not configured, the terminal may performtransmission using the secondary bandwidth part.

As a second method, a base station may inform a terminal (e.g.,narrowband terminal) supporting the same or similar bandwidth (e.g., 20MHz) as the size of the secondary bandwidth part (e.g., 20 MHz) that thesecondary bandwidth part is regarded as a system bandwidth (or carrierbandwidth, channel bandwidth) or effective PRBs of a narrowband carrier,and the secondary bandwidth part is recognized as a carrier. A time whenthe terminal regards the secondary bandwidth part as a carrier may bedefined based on a specific operation of the base station or theterminal. Alternatively, the time when the terminal regards thesecondary bandwidth part as a carrier may be derived from a time pointat which the base station informs the terminal through signaling. Forexample, the base station may transmit to the terminal an indicator(e.g., an indicator having a size of 1 bit) instructing the terminal toregard the secondary bandwidth part as a carrier.

In order to prevent the terminal from reconfiguring the bandwidth partwhen considering the secondary bandwidth part as a carrier, the size(e.g., the number of PRBs) of the secondary bandwidth part may be set toone (e.g., the number of PRBs corresponding to a system bandwidth) ofsystem bandwidths supported by the NR. For example, when the NR supportsa system bandwidth of 20 MHz, the size of the secondary bandwidth partmay be set to 20 MHz. Alternatively, when the NR supports a carrier with100 PRBs for a specific subcarrier spacing, the secondary bandwidth partmay be composed of 100 consecutive PRBs in the frequency domain.

On the other hand, the characteristics of the downlink secondarybandwidth part may be equally applied to the downlink anchor bandwidthpart. For example, the respective PDSCH for transmission of Msg4 orunicast data may be transmitted in the downlink anchor bandwidth part.The UE-specific search space in which the DCI scheduling the PDSCH fortransmission of each of Msg4 and unicast data may be configured withinthe anchor bandwidth part. The UE-specific search space may be logicallyassociated with the anchor bandwidth part. In this case, the terminalmay monitor both the common search space and the UE-specific searchspace in the anchor bandwidth part.

When a data channel is scheduled by a common DCI received in the commonsearch space, the terminal may assume that a DMRS sequence of the datachannel is generated based on a local PRB index in the anchor bandwidthpart. For example, the DMRS sequence of the data channel may begenerated based on the first PRB (e.g., PRB #0) or the first subcarrier(e.g., subcarrier #0) of the first PRB within the anchor bandwidth part,and may be mapped to REs. The common DCI received in the common searchspace may be a specific common DCI.

When the data channel is scheduled by the DCI received in theUE-specific search space, the terminal may assume that the DMRS sequenceof the data channel is generated based on an RB index of a common RBgrid. For example, the DMRS sequence of the data channel may begenerated based on the first RB (e.g., RB #0) of the common RB grid orthe first subcarrier (e.g., subcarrier #0) of the first RB, and may bemapped to REs. This method may be referred to as ‘Method 110’.

In Method 110, the data channel scheduled by a specific common DCI maybe a PDSCH including RMSI (hereinafter referred to as an ‘RMSI PDSCH’).Since the reception time of the RMSI PDSCH is before the acquisitiontime of the RMSI configuration information, the terminal may not use thecommon RB grid for RE mapping of the DMRS sequence of the RMSI PDSCH.Therefore, the RE mapping of the DMRS sequence of the RMSI PDSCH may bedefined based on the anchor bandwidth part. On the other hand, thereception time of Msg4 or unicast data may be after the reception timeof the RMSI. Therefore, after acquiring the configuration information ofthe common RB grid from the RMSI, the terminal may generate the DMRS ofthe PDSCH based on the common RB grid, and map the DMRS to REs.

Meanwhile, the terminal operating in the RRC connected state may receivethe RMSI PDSCH in a bandwidth part other than the anchor bandwidth part.In this case, the DMRS generation and RE mapping of the RMSI PDSCH maybe defined based on the common RB grid. That is, Method 110 may beapplied to the anchor bandwidth part.

Configuration of Reserved Resources

In order to provide forward compatibility, specific time-frequencyresources may be configured as reserved resources in the NR. Theterminal may not transmit or receive any signal basically in thetime-frequency resources configured as the reserved resources. The basestation may configure the reserved resources via an RRC signaling (e.g.,signaling of system information, UE-specific RRC signaling) or aphysical layer signaling (e.g., common DCI, group common DCI, downlinkscheduling DCI). Also, the base station may configure the reservedresources by a combination of RRC signaling and physical layersignaling. That is, the base station may transmit configurationinformation of the reserved resources to the terminal using at least oneof RRC signaling and physical layer signaling. A time domainconfiguration unit (unit or granularity) of the reserved resources maybe T symbols, and a frequency domain configuration unit of the reservedresources may be K subcarriers or L PRB s. Here, each of T, K, and L maybe a natural number.

For example, when T=1 and L=1, the reserved resources may be configuredas a combination of symbol(s) and PRB(s). The reserved resources may beconfigured in at least one of the time domain and the frequency domain.For example, when the reserved resources are configured only in the timedomain, it may be assumed that the entire band of the carrier or theentire band of the bandwidth part in which the reserved resources areconfigured is configured as the reserved resources in the frequencydomain. On the other hand, when the reserved resources are configuredonly in the frequency domain, it may be assumed that all resources inthe time domain are configured as the reserved resources.

Meanwhile, when one or more bandwidth parts are configured in theterminal, the base station may configure reserved resources for eachbandwidth part. This method may be referred to as ‘Method 300’. InMethod 300, the reserved resources in the time-frequency domain may beconfigured according to a numerology (e.g., subcarrier spacing and CPlength) of each of the bandwidth parts, and may be limited to physicalresources occupied by each of the bandwidth parts. In particular, thereserved resources in the frequency domain may be configured to the PRBsor subcarriers that constitute each of the bandwidth parts. Thebandwidth part may include all time resources in the time domain, andthe reserved resources may be configured in symbols or slots in the timedomain. The reserved resources may be configured in each of the uplinkbandwidth part and the downlink bandwidth part.

When first reserved resources for a terminal is configured in a firstbandwidth part by Method 300, the terminal may assume that any physicallayer signal or channel (e.g., physical layer signal or channellogically associated with the first bandwidth part) is not transmittedthrough the first bandwidth part in the first reserved resources. Here,the physical layer signal may be DMRS, CSI-RS, SRS, phase trackingreference signal (PT-RS), or the like, which is configured or scheduledin the first bandwidth part, and the physical layer channel may be acontrol channel, a data channel, or the like, which is scheduled in thefirst bandwidth part. In particular, when a resource region of the datachannel (e.g., PDSCH, PUSCH) scheduled in the first bandwidth partincludes the first reserved resources, the data channel may betransmitted or received as rate-matched around the first reservedresources.

On the other hand, the terminal may transmit or receive a physical layersignal or channel (e.g., physical layer signal or channel logicallyassociated with a second bandwidth part) in a different bandwidth part(e.g., the second bandwidth part) in the first reserved resources. Here,the physical layer signal may be DMRS, CSI-RS, SRS, PT-RS, or the like,which is configured or scheduled in the second bandwidth part instead ofthe first bandwidth part, and the physical layer channel may be acontrol channel, a data channel, or the like, which is configured orscheduled in the second bandwidth part instead of the first bandwidthpart. The method described above may be applied to either or both caseswhere the first bandwidth part is activated or deactivated. The firstbandwidth part and the second bandwidth part may be basically bandwidthparts having the same transmission direction (e.g., downlink or uplink).Alternatively, the transmission direction of the first bandwidth partmay be different from the transmission direction of the second bandwidthpart. For example, the first bandwidth part may be a downlink bandwidthpart, and the second bandwidth part may be an uplink bandwidth part.

For example, when the first downlink bandwidth part composed of 50contiguous PRBs is configured in the terminal, the base station mayconfigure reserved resources for the first downlink bandwidth part inthe terminal. For example, when the first downlink bandwidth part iscomposed of PRBs #0 to #49 (i.e., local PRBs #0 to #49 of the firstdownlink bandwidth part), the base station may configure the PRBs #10 to#19 of the first bandwidth part as reserved resources in the frequencydomain, and may configure the fifth and sixth symbols in each slot asreserved resources in the time domain. The terminal may assume that anyphysical layer signal or channel is not transmitted or received in REscorresponding to a combination of the PRBs and symbols configured by thebase station as the reserved resources.

Here, a physical layer channel transmitted through the first downlinkbandwidth part may be a PDCCH logically associated with the firstdownlink bandwidth part, a PDSCH scheduled by the PDCCH, and the like,and the physical layer signal transmitted through the first downlinkbandwidth part may be a DMRS used for demodulating the PDCCH and thePDSCH, a reference signal configured in the first downlink bandwidthpart, and the like. Also, the terminal may not perform other operations(e.g., CSI/radio resource management (RRM)/radio link monitoring (RLM)measurement operations) defined for the first downlink bandwidth part inthe reserved resources configured in the first downlink bandwidth part.

In the following embodiments, a case where the base station furtherconfigures the second downlink bandwidth part in the same carrier to theterminal will be described. Here, a frequency region of the seconddownlink bandwidth part may overlap a frequency region of the firstdownlink bandwidth part. For example, the second downlink bandwidth partmay be composed of 100 contiguous PRBs (e.g., PRBs #0 to #99), and afrequency region occupied by the PRBs #0 to #49 may overlap with thefrequency region of the first downlink bandwidth part. In this case, thebase station may configure reserved resources for the second downlinkbandwidth part in the terminal. For example, the base station mayconfigure the PRBs #30 to #39 (i.e., local PRBs #30 to #39 of the seconddownlink bandwidth part) in the second downlink bandwidth part asreserved resources. The terminal may assume that any physical layersignal or channel is not transmitted through the second downlinkbandwidth part in the reserved resources (e.g., PRBs #30 to #39)configured by the base station. Also, the terminal may not perform otheroperations (e.g., CSI/RRM/RLM measurement) defined for the seconddownlink bandwidth part in the reserved resources configured in thesecond downlink bandwidth part.

Meanwhile, the terminal may expect to receive a physical channel signalor channel through the second downlink bandwidth part in the reservedresources configured for the first downlink bandwidth part. For example,the terminal may expect to receive a PDSCH scheduled in the seconddownlink bandwidth part in the reserved resources (e.g., REscorresponding to a combination of the PRBs #10 to #19 and the fifth andsixth symbols in each slot) configured for the first downlink bandwidthpart. For example, the PDSCH scheduled for the second downlink bandwidthpart may be a mini-slot PDSCH for Ultra Reliable Low LatencyCommunication (URLLC) transmission.

That is, the terminal may receive enhanced Mobile Broadband (eMBB) datathrough the first downlink bandwidth part, and receive URLLC datathrough the second downlink bandwidth part. The base station may reservethe corresponding reserved resources as physical resources for the URLLCtransmission of the second downlink bandwidth part by configuring thereserved resources in the first downlink bandwidth part. That is, a datachannel (e.g., data channel for eMBB transmission) scheduled in thefirst downlink bandwidth part may be transmitted as rate-matched aroundthe reserved resources configured in the first downlink bandwidth part,and accordingly the reserved resources configured within the firstdownlink bandwidth part may be used for transmission of a data channel(e.g., data channel for URLLC transmission) scheduled in the seconddownlink bandwidth part. The reservation of physical resources may beconfigured through at least one of a higher layer signaling and aphysical layer signaling as described above. Here, overlapped bandwidthparts (e.g., the first downlink bandwidth part and the second downlinkbandwidth part) may be activated simultaneously for reservedresource-based communication.

Conversely, the terminal may expect to receive a physical layer signalor channel through the first bandwidth part in the reserved resourcesconfigured for the second downlink bandwidth part. For example, theterminal may expect to receive a PDSCH scheduled in the first downlinkbandwidth part in the PRBs #30 to #39 configured as reserved resourcesfor the second downlink bandwidth part. In this case, the first downlinkbandwidth part and the second downlink bandwidth part may be activatedsimultaneously in the terminal. When a plurality of bandwidth parts areconfigured in the terminal, the terminal may perform a transmission andreception operation of a physical layer signal or channel through onebandwidth part using reserved resources configured for another bandwidthpart. The embodiments described above may be equally applied to theuplink bandwidth part.

FIG. 3 is a conceptual diagram illustrating a first embodiment of areserved resource configuration method according to Method 300 in acommunication system.

Referring to FIG. 3 , a first downlink bandwidth part and a seconddownlink bandwidth part may be configured in one terminal, and afrequency region of the first downlink bandwidth part may overlap with afrequency region of the second downlink bandwidth part. The base stationmay configure some resources (i.e., a resource region having a durationT2) of the first downlink bandwidth part in a resource region overlappedbetween the first downlink bandwidth part and the second downlinkbandwidth part as reserved resources, and transmit configurationinformation of the reserved resources to the terminal. Here, thereserved resources may be configured as a resource region in which aPDSCH can be transmitted in the second downlink bandwidth part. In thiscase, the reserved resources may be used to multiplex two PDSCHs withdifferent transmission durations.

The terminal may receive a PDSCH having a transmission duration of T1through the remaining resource regions excluding the reserved resourcesin the first downlink bandwidth part, and receive a PDSCH having atransmission duration T2 (e.g., a PDSCH scheduled in the second downlinkbandwidth part) through the reserved resources. Here, the PDSCH (e.g.,the PDSCH transmitted and received in the first downlink bandwidth part)may be rate-matched around the reserved resources. The terminal mayassume that the PDSCH scheduled in the first downlink bandwidth part isnot received in the reserved resources having the duration T2. T1 and T2may each be a time duration occupied by one or more consecutive symbols.For example, T1 may be a transmission duration of a PDSCH by slot-basedscheduling, and T2 may be a transmission duration of a PDSCH by amini-slot-based scheduling. For example, T1 may be used for transmissionof eMBB data, and T2 may be used for transmission of URLLC data.

Also, the operations described above may be applied to uplinktransmission. For example, the first uplink bandwidth part and thesecond uplink bandwidth part may be configured in one terminal, and afrequency region of the first uplink bandwidth part may overlap with afrequency region of the second uplink bandwidth part. The base stationmay configure some resources of the first uplink bandwidth part in aresource region overlapped between the first uplink bandwidth part andthe second uplink bandwidth part as reserved resources, and transmitconfiguration information of the reserved resources to the terminal.Here, the reserved resources may be configured as a resource region inwhich a PDSCH can be transmitted in the second uplink bandwidth part.

The base station may receive a PUSCH having a transmission duration ofT1 through the remaining resource regions excluding the reservedresources in the first uplink bandwidth part, and receive a PUSCH havinga transmission duration T2 (e.g., a PDSCH scheduled in the second uplinkbandwidth part) through the reserved resources. Here, the PUSCH (e.g.,the PDSCH transmitted and received in the first uplink bandwidth part)may be rate-matched around the reserved resources. The terminal mayassume that the PUSCH scheduled in the first uplink bandwidth part isnot transmitted in the reserved resources having the duration T2.

According to the embodiment described above (e.g., the embodimentaccording to Method 300), the base station may efficiently transmit eMBBdata and URLLC data to the terminal. That is, a resource region forURLLC data transmission may be reserved in advance, and a PDSCH or PUSCHfor eMBB data may not be mapped to the reserved resource region.Therefore, when URLLC data is generated, the base station may quicklytransmit the URLLC data to the terminal through the reserved resourceregion. When a resource region for URLLC data transmission is notreserved and the PDSCH or PUSCH for eMBB data transmission is alreadyscheduled in a slot at the time when the URLLC data is generated, thebase station may perform scheduling for transmission of the URLLC dataafter completing the transmission of the PDSCH or PUSCH. Alternatively,the base station may transmit a PDSCH or PUSCH for the URLLC data in theresource region of the already-scheduled PDSCH or PUSCH.

The scheme of scheduling the URLLC data in a resource region aftercompleting the transmission of the already-scheduled PDSCH or PUSCH maynot satisfy URLLC transmission requirements since a scheduling timelatency is caused. The scheme of transmitting the PDSCH or PUSCH for theURLLC data in a resource region of the already-scheduled PDSCH or PUSCHmay correspond to a preemption scheme of the resource for transmissionof the URLLC data. In this case, the complexity of the transceiver mayincrease, and further signaling may be required to indicate to theterminal whether or not the preemption is applied.

In Method 300, a cross bandwidth part scheduling scheme may be used. Forexample, when a PDCCH of the first downlink bandwidth part schedules aPDSCH of the second downlink bandwidth part, the PDSCH may be regardedas a physical channel transmitted through the second downlink bandwidthpart even though the PDSCH is scheduled through the first downlinkbandwidth part. Accordingly, when the first downlink bandwidth part andthe second downlink bandwidth part are activated simultaneously or onlythe second downlink bandwidth part is active, the terminal may receivethe PDSCH of the second downlink bandwidth part scheduled through thefirst downlink bandwidth part in the reserved resources in the firstdownlink bandwidth part.

Meanwhile, a plurality of carriers may be configured based on Method300. For example, the base station may configure reserved resources foreach carrier, and may inform the terminal of configuration informationof the reserved resources through a signaling procedure. When each ofthe plurality of carriers is defined in different frequency regions, itmay be natural that the reserved resources are configured for eachcarrier. When frequency regions of a plurality of carriers configuredand activated in one terminal are partially or entirely overlapped, thereserved resources may be configured in a frequency region overlappedamong the plurality of carriers.

Therefore, a configuration operation of the reserved resources andterminal operations in the reserved resources may be defined for eachcarrier. For example, when a first carrier and a second carrierconfigured for a terminal are activated, the terminal may assume that aphysical layer signal or channel is not transmitted through the firstcarrier in the reserved resources configured for the first carrier, andthat a physical layer signal or channel is not transmitted through thesecond carrier in the reserved resources configured for the secondcarrier.

On the other hand, when the reserved resources of the first carrieroverlap with a physical resource of the second carrier, the terminal mayexpect that the physical layer signal or channel through the secondcarrier is transmitted in the reserved resources of the first carrier.Also, when the reserved resources of the second carrier overlap with aphysical resource of the first carrier, the terminal may expect that thephysical layer signal or channel through the first carrier istransmitted in the reserved resources of the second carrier. That is,when frequency regions of a plurality of carriers configured in aterminal are overlapped, resources reserved for a specific carrier maybe used to transmit a physical layer signal or channel of anothercarrier.

The SFI may be used for physical layer signaling of reserved resources.The SFI may be included in a DCI transmitted through a group commonPDCCH. The SFI may be used to inform the terminal of types of symbols(e.g., downlink symbol, uplink symbol, unknown symbol) that constituteeach of one or more slots. The terminal may expect to receive a downlinksignal or channel in the downlink symbols identified based on the SFI,expect to transmit an uplink signal or channel in the uplink symbolsidentified based on the SFI, and assume that that any signal or channelis not transmitted or received in the unknown symbols identified basedon the SFI. Therefore, the operation of the terminal in the unknownsymbols may be similar to the operation of the terminal in the reservedresources.

When a plurality of bandwidth parts are configured in one terminal forone transmission direction (e.g., downlink or uplink), the base stationmay transmit a group common PDCCH to the terminal for each of theplurality of bandwidth parts, and a DCI transmitted through the groupcommon PDCCH may include a SFI of each of the plurality of bandwidthparts. Alternatively, the SFI of each of the plurality of bandwidthparts may be included in the DCI transmitted through one group commonPDCCH. For example, the DCI transmitted through one group common PDCCHmay include a plurality of SFIs, information indicating a bandwidth partcorresponding to each of the plurality of SFIs, and the like.Alternatively, the information indicating a bandwidth part correspondingto each of the plurality of SFIs may be preconfigured in the terminalthrough a higher layer signaling instead of the DCI. The operation andassumption of the terminal in the unknown region (e.g., unknown symbols)in a slot may be limited to the corresponding bandwidth part (e.g.,overlapped bandwidth part) similarly to Method 300. This method may bereferred to as ‘Method 310’.

Meanwhile, the terminal may apply one SFI received through the groupcommon PDCCH to a plurality of bandwidth parts. For example, theterminal may receive at most one group common PDCCH in one carrier, andone group common PDCCH may include one SFI. In this case, a bandwidthpart (e.g., effective bandwidth part) to which the SFI included in thegroup common PDCCH is applied and a bandwidth part (e.g., ineffectivebandwidth part) to which the SFI included in the group common PDCCH isnot applied may be preconfigured by a higher layer signaling. Thedownlink region, the uplink region, and the unknown region configured bythe SFI may be effective only in the effective bandwidth part.Configuration information of the effective and ineffective bandwidthparts may be transmitted through the group common PDCCH together withthe SFI.

Since the NR supports a plurality of numerologies, a referencesubcarrier spacing for interpreting a slot format configured by the SFImay be considered. The base station may configure a reference subcarrierspacing of a dynamic slot format in the terminal. The referencesubcarrier spacing of the dynamic slot format may be configured througha higher layer signaling procedure (e.g., RRC signaling procedure) or aphysical layer signaling procedure (e.g., DCI signaling procedure). Whenthe physical layer signaling procedure is used, the SFI may include thereference subcarrier spacing.

In this case, only a bandwidth part configured with a subcarrier spacingequal to or greater than the reference subcarrier spacing may be limitedto be configured as the effective bandwidth part to which the SFI isapplied. That is, when a subcarrier spacing of a bandwidth part issmaller than the reference subcarrier spacing, the interpretation of theslot format in the corresponding bandwidth part may be ambiguous. Thisproblem will be described in detail in the embodiments related toconfiguration of a semi-static slot format below. When a subcarrierspacing of a bandwidth part is smaller than the reference subcarrierspacing, the slot format of the bandwidth part may be configured to beequal to or similar to each of Method 400, Method 410, and Method 420.

In this case, the effective bandwidth part and the ineffective bandwidthpart may overlap in a specific resource region, and a resource regionconfigured as unknown symbols by the SFI may exist in the specificoverlapping specific resource region. Also in this case, Method 300 maybe similarly applied. That is, the terminal may assume that a physicallayer signal or channel is not transmitted and received through theeffective bandwidth part in the unknown region, and may expect that aphysical layer signal or channel is transmitted and received through theineffective bandwidth part in the unknown region.

Configuration of a Semi-Static Slot Format

In the following embodiments, methods of configuring a semi-static slotformat will be described. A repetition period of the semi-static slotformat may include 0.5 ms, 0.625 ms, 1 ms, 1.25 ms, 2 ms, 2.5 ms, 5 ms,10 ms, and the like, and some repetition periods of the semi-static slotformat may only be applied to a specific subcarrier spacing. Also, asemi-static slot format may be configured such that a slot format havinga repetition period of T₁ ms and a slot format having a repetitionperiod of T₂ ms are continuously allocated. In this case, a repetitionperiod of the semi-static slot format may be (T₁+T₂) ms, and each of T₁and T₂ may be configured to be one among the repetition periodsdescribed above.

The order of transmission directions of a cell-specific semi-static slotformat may be configured to ‘downlink→unknown→uplink’ within one period.The unknown symbol may be regarded as a symbol whose transmissiondirection is not strictly defined, but in the embodiments of the presentinvention, the ‘unknown’ may also be regarded as a type of transmissiondirection for convenience. Cell specific semi-static slot formatinformation may include x1, x2, y1, and y2. x1 may be the number of fulldownlink slots allocated in a starting region of the repetition period,and x2 may be the number of downlink symbols allocated after the x1downlink slots. y1 may be the number of full uplink slots allocated inan ending region of the repetition period, and y2 may be the number ofuplink symbols allocated before the y1 uplink slots. The duration notrepresented by x1, x2, y1, and y2 may be regarded as an unknownduration.

The reference subcarrier spacing used to configure the semi-static slotformat may be configured in the terminal. For example, the referencesubcarrier spacing may be system information, and the referencesubcarrier spacing may be broadcast with configuration information ofthe cell specific semi-static slot format. The reference subcarrierspacing may be set to one of available subcarrier spacings (e.g., kHz,30 kHz, 60 kHz, and 120 kHz) for data transmission.

FIG. 4 is a conceptual diagram illustrating a first embodiment of asemi-static slot format in a communication system, and FIG. 5 is aconceptual diagram illustrating a second embodiment of a semi-staticslot format in a communication system.

Referring to FIG. 4 , a reference subcarrier spacing may be 15 kHz, anda repetition period of a semi-static slot format may be 5 ms, and (x1,x2, y1, y2) may be configured to (2, 5, 1, 3). In this case, onerepetition period may be composed of 5 slots. Referring to FIG. 5 , areference subcarrier spacing may be 30 kHz, and a repetition period of asemi-static slot format may be 5 ms, and (x1, x2, y1, y2) may beconfigured to (2, 5, 1, 3). In this case, one repetition period may becomposed of 10 slots. As described above, even when the repetitionperiod and (x1, x2, y1, y2) are the same, a slot structure may varyaccording to the reference subcarrier spacing. For example, when therepetition period and (x1, x2, y1, y2) are the same, a ratio of theunknown duration may be increased as the reference subcarrier spacing islarger.

Meanwhile, the configuration information of the bandwidth part mayinclude a subcarrier spacing. The base station may inform the terminalof a subcarrier spacing used in a bandwidth part when configuring adownlink bandwidth part or an uplink bandwidth part in the terminal.Therefore, the subcarrier spacing of the bandwidth part configured inthe terminal may be different from the reference subcarrier spacing ofthe semi-static slot format. When the subcarrier spacing of thebandwidth part differs from the reference subcarrier spacing of thesemi-static slot format, methods for interpreting and applying asemi-static slot format in the bandwidth part may be defined.

FIG. 6 is a conceptual diagram illustrating a first embodiment ofconfiguration of a semi-static slot format and a bandwidth part in acommunication system.

Referring to FIG. 6 , a repetition period of a semi-static slot formatmay be 0.5 ms, and a reference subcarrier spacing may be 60 kHz. Theremay be 2 slots (e.g., slots #n and #(n+1)) in one repetition period, andthe order of symbols allocated in the 2 slots may be ‘downlinksymbol→unknown symbol→uplink symbol’. Here, ‘D’ may indicate a downlinksymbol, ‘X’ may indicate an unknown symbol, ‘U’ may indicate an uplinksymbol, and ‘C’ may indicate a symbol whose transmission direction is tobe defined according to a transmission direction collision, etc.

In this case, a subcarrier spacing of a bandwidth part configured in theterminal may vary. When a subcarrier spacing of a bandwidth part is 60kHz, the subcarrier spacing of the bandwidth part matches the referencesubcarrier spacing, so that the terminal may have no problem ininterpreting the slot format. On the other hand, when a subcarrierspacing of a bandwidth part is smaller than 60 kHz, there may be asymbol C whose transmission direction is not determined. For example,when a subcarrier spacing of a downlink bandwidth part and an uplinkbandwidth part is 30 kHz, one symbol of the bandwidth part correspondsto 2 symbols according to the semi-static slot format, so that onesymbol of the bandwidth part may correspond to ‘downlink symbol andunknown symbol’, ‘uplink symbol and unknown symbol’, or the likeaccording to the semi-static slot format. In this case, it may bedifficult to determine the transmission direction of the symbol of thebandwidth part only by the configuration information of the semi-staticslot format.

Alternatively, when a subcarrier spacing of a downlink bandwidth partand an uplink bandwidth part is 15 kHz, one symbol of the bandwidth partcorresponds to 4 symbols according to the semi-static slot format, sothat one symbol of the bandwidth part may correspond to ‘downlink symboland unknown symbol’, ‘uplink symbol and unknown symbol’, ‘downlinksymbol and uplink symbol’, or the like according to the semi-static slotformat. In this case, it may be difficult to determine the transmissiondirection of the symbol of the bandwidth part only by the configurationinformation of the semi-static slot format.

On the other hand, when the subcarrier spacing of the bandwidth part isgreater than the reference subcarrier spacing of the semi-static slotformat, the above-described problem may not occur.

FIG. 7 is a conceptual diagram illustrating a second embodiment ofconfiguration of a semi-static slot format and a bandwidth part in acommunication system.

Referring to FIG. 7 , a repetition period of a semi-static slot formatmay be 1 ms, and a reference subcarrier spacing may be 15 kHz. There maybe one slot (e.g., slot #n) in one repetition period, and the order ofsymbols allocated in the one slot may be ‘downlink symbol→unknownsymbol→uplink symbol’. In this case, the subcarrier spacing of thebandwidth part configured in the terminal may be greater than 15 kHz(i.e., the reference subcarrier spacing of the semi-static slot format).For example, when the subcarrier spacing of the bandwidth part is 30 kHzor 60 kHz, since one symbol of the bandwidth part always corresponds toone symbol according to the semi-static slot format, transmissiondirections of all the symbols constituting the bandwidth part within therepetition period may be clearly determined only by the configurationinformation of the semi-static slot format.

In the following embodiments, methods for solving the problem describedwith reference to FIG. 6 (i.e., the problem in which the subcarrierspacing of the bandwidth part is configured to be smaller than thereference subcarrier spacing of the semi-static slot format) will bedescribed.

In a first method, the subcarrier spacing of the bandwidth part may beset to be greater than or equal to the reference subcarrier spacing ofthe semi-static slot format. In this case, the terminal may not expectthat the subcarrier spacing of the bandwidth part is configured to besmaller than the reference subcarrier spacing of the semi-static slotformat. This method may be referred to as ‘Method 400’. When Method 400is used and the subcarrier spacing of the bandwidth part is greater thanthe reference subcarrier spacing of the semi-static slot format, theterminal may identify the slot format of the bandwidth part based on themethod described with reference to FIG. 7 .

When subcarrier spacing candidate(s) that can be configured as thesubcarrier spacing of the bandwidth part are predefined for eachfrequency band, the smallest subcarrier spacing among the subcarrierspacing candidate(s) may be defined as the reference subcarrier spacingof the semi-static slot format. This method may be referred to as‘Method 401’. For example, when the subcarrier spacing of the bandwidthpart in a specific frequency band is set to 15 kHz, 30 kHz, or 60 kHz,the reference subcarrier spacing of the semi-static slot format may bedefined as 15 kHz. However, when a bandwidth part having a subcarrierspacing of 15 kHz is not used in a specific frequency band, theconfiguration of the semi-static slot format according to Method 401 maybe inefficient. For example, when only a subcarrier spacing of 30 kHz isused for data transmission in a specific frequency band, the referencesubcarrier spacing in the semi-static slot format may be preferably setto 30 kHz.

In order to solve the disadvantage of Method 401, ‘Method 402’ may beused. In Method 402, a plurality of reference subcarrier spacings may beallowed per frequency band, and the reference subcarrier spacing of thesemi-static slot format may be set to be equal to or less than thesubcarrier spacing of the bandwidth part. According to Method 402, thebase station may use the smallest subcarrier spacing among subcarrierspacings actually used for data transmission in a cell or a carrier asthe reference subcarrier spacing of the semi-static slot format.Therefore, when Method 402 is used, the inefficiency according to Method401 may not occur.

Even when Method 402 is used, all terminals in the cell should use thesame reference subcarrier spacing, so that a granularity of thesemi-static slot format for a terminal using a subcarrier spacinggreater than the reference subcarrier spacing may not be fine. Forexample, when one terminal operates in a bandwidth part having asubcarrier spacing of 15 kHz and the other terminal operates in abandwidth part having a subcarrier spacing of 60 kHz, the referencesubcarrier spacing of the semi-static slot format may be set to 15 kHz.In this case, the semi-static slot format for the terminal operating inthe bandwidth part having a subcarrier spacing of 60 may be configuredin four symbol units. This may be inappropriate for URLLC transmission.Thus, according to Method 400, Method 401, or Method 402, it may bedifficult to simultaneously transmit eMBB data and URLLC data in thesame cell.

In a second method for solving the problem described with reference toFIG. 6 , it may be allowed that the subcarrier spacing of the bandwidthpart is set to be smaller than the reference subcarrier spacing of thesemi-static slot format, and a transmission direction of a specificsymbol may be determined by a predefined rule when a collision oftransmission directions occurs in the specific symbol of a bandwidthpart (e.g., when the specific symbol of the bandwidth part correspondsto a plurality of symbols having different transmission directionsaccording to the semi-static slot format). This method may be referredto as ‘Method 410’. Further, ‘Method 411’ to ‘Method 416’ which are thedetailed methods of Method 410 may be defined.

In Method 411, when a specific symbol of the bandwidth part correspondsto ‘downlink symbol and unknown symbol’, ‘unknown symbol and uplinksymbol’ or ‘downlink symbol, unknown symbol, and uplink symbol’, atransmission direction of the specific symbol in the bandwidth part maybe regarded as ‘unknown’. That is, when transmission directionsaccording to the semi-static slot format are collided in one symbol ofthe bandwidth part, a rule that the unknown takes precedence over thedownlink and uplink may be used.

Conversely, when the transmission directions according to thesemi-static slot format in one symbol of the bandwidth part collide, arule that the downlink and uplink take precedence over the unknown maybe used. This method may be referred to as ‘Method 412’. According toMethod 412, the unknown duration according to the semi-static slotformat may be overridden to be a downlink duration or an uplink durationin the bandwidth part. However, it is not desirable that the unknownduration is overridden to a different transmission direction (e.g.,downlink or uplink) when the unknown duration is used for ensuringflexibility of the transmission direction or for protecting a specificsignal. Also, according to the result of the overriding, a slotstructure in which an unknown duration does not exist between thedownlink duration and the uplink duration may occur. In order to avoidsuch the case, it may be preferable to use Method 411 rather than Method412.

Also, when a specific symbol of the bandwidth part corresponds to‘downlink symbol and uplink symbol’ according to the semi-static slotformat, a transmission direction of the specific symbol in the bandwidthpart may be set to a predefined transmission direction among downlinkand uplink. This method may be referred to as ‘Method 413’.Alternatively, the transmission direction of the specific symbol in thebandwidth part may be set to unknown. This method may be referred to as‘Method 414’. According to Method 413, cross-link interference mayoccur. Therefore, it may be desirable that the transmission direction ofthe specific symbol in which a transmission direction collision occursin the bandwidth part is regarded as the unknown. Even when thetransmission direction of the specific symbol in which a transmissiondirection collision occurs in the bandwidth part is regarded as theunknown by Method 414, the specific symbol regarded as the unknown maythen be used for downlink transmission or uplink transmission byscheduling of the base station.

Alternatively, when a transmission direction collision according to thesemi-static slot format occurs in a specific symbol of the bandwidthpart, the transmission direction of the specific symbol in the bandwidthpart may be set to a transmission direction occupying a relatively largeduration in the specific symbol. This method may be referred to as‘Method 415’. One of Method 411 to Method 414 may be used when thelengths of the durations (e.g., downlink duration, unknown duration, anduplink duration) are identical.

FIG. 8 is a conceptual diagram illustrating a first embodiment of a slotformat of a bandwidth part according to Method 411 in a communicationsystem.

Referring to FIG. 8 , a repetition period of a semi-static slot formatmay be 0.5 ms, and a reference subcarrier spacing may be 60 kHz. When asubcarrier spacing of a downlink bandwidth part and an uplink bandwidthpart is 30 kHz, a collision between the downlink and the unknown mayoccur in the fourth and ninth symbols in the downlink bandwidth partwithin one repetition period of the semi-static slot format, and acollision between the uplink and the unknown may occur in the fifth andtwelfth symbols in the uplink bandwidth part within one repetitionperiod of the semi-static slot format. According to Method 411, thefourth and ninth symbols in the downlink bandwidth part may be regardedas unknown symbols, and the fifth and twelfth symbols in the uplinkbandwidth part may be regarded as unknown symbols.

Here, since the collision between the downlink and the unknown may occurin the fourth and ninth symbols in the downlink bandwidth part, thefourth and ninth symbols regarded as unknown symbols in the downlinkbandwidth part may be overridden only to be downlink symbols. Since thecollision between the uplink and the unknown may occur in the fifth andtwelfth symbols in the uplink bandwidth part, the fifth and twelfthsymbols regarded as unknown symbols in the uplink bandwidth part may beoverridden only to be uplink symbols. That is, the type of the unknownin the fourth and ninth symbols in the downlink bandwidth part may bedifferent from the type of the unknown in the fifth and twelfth symbolsin the uplink bandwidth part.

When a subcarrier spacing of a downlink bandwidth part and an uplinkbandwidth part is 15 kHz, a collision between the downlink and theunknown may occur in the second and fifth symbols in the downlinkbandwidth part within one repetition period of the semi-static slotformat, and a collision between the uplink and the unknown may occur inthe third and sixth symbols in the uplink bandwidth part within onerepetition period of the semi-static slot format. According to Method411, the second and sixth symbols in the downlink bandwidth part may beregarded as unknown symbols, and the third and sixth symbols in theuplink bandwidth part may be regarded as unknown symbols.

Here, since the collision between the downlink and the unknown may occurin the second and fifth symbols in the downlink bandwidth part, thesecond and fifth symbols regarded as unknown symbols in the downlinkbandwidth part may be overridden only to be downlink symbols. Since thecollision between the uplink and the unknown may occur in the third andsixth symbols in the uplink bandwidth part, the third and sixth symbolsregarded as unknown symbols in the uplink bandwidth part may beoverridden only to be uplink symbols.

Meanwhile, when a subcarrier spacing of a downlink bandwidth part and anuplink bandwidth part is 15 kHz, a slot of a bandwidth part within onerepetition period of a semi-static slot format may be configured as ahalf slot comprising 7 symbols. Therefore, a slot format of thebandwidth part may be repeated in 7 symbol units. In this case, theremay be a plurality of unknown durations that are not intended in oneslot. Therefore, one repetition period of the semi-static slot formatmay be configured to comprise n slots of the bandwidth part, and n maybe an integer greater than or equal to 1. This method may be referred toas ‘Method 416’. The base station may appropriately determineconfiguration parameters (e.g., repetition period, reference subcarrierspacing) of the semi-static slot format and configuration parameter(e.g., subcarrier spacing) of the bandwidth part, so as to ensure theconditions of Method 416.

Alternatively, when Method 416 is not used, one repetition period of theslot format in the bandwidth part may be allowed to include a part ofone slot (e.g., half slot). In this case, it is preferable that onerepetition period of the slot format in the bandwidth part includes mfull symbols. m may be an integer equal to or greater than 1.

In a third method for solving the problem described with reference toFIG. 6 , semi-static slot formats for different reference subcarrierspacings may be configured. That is, a plurality of semi-static slotformats may be configured to the terminal. This method may be referredto as ‘Method 420’. For example, when a reference subcarrier spacing ofthe semi-static slot format is set to 15 kHz, 30 kHz, or 60 kHz, thebase station may configure a semi-static slot format having a referencesubcarrier spacing of 15 kHz (hereinafter referred to as a ‘first slotformat’), and a semi-static slot format having a reference subcarrierspacing of 30 kHz (hereinafter referred to as a ‘second slot format’).

When a downlink bandwidth part and an uplink bandwidth part areconfigured in the terminal, a semi-static slot format having a referencesubcarrier spacing identical to a subcarrier spacing of the bandwidthpart may be applied to the corresponding bandwidth part. This method maybe referred to as ‘Method 426’. When a downlink bandwidth part and anuplink bandwidth part having a subcarrier spacing of kHz are configuredin the terminal, the second slot format may be applied to thecorresponding bandwidth part.

When Method 420 and Method 426 are used, the terminal may expect thatthe subcarrier spacing of the bandwidth part is set to one of thereference subcarrier spacing(s) according to the configuration of thesemi-static slot format. When the subcarrier spacing of the bandwidthpart does not match the reference subcarrier spacing, the terminal mayregard the configuration of the bandwidth part as erroneous, and may notperform operations related to the corresponding bandwidth part. Forexample, when the terminal expects a bandwidth part having a 15 kHz or30 kHz subcarrier spacing to be configured, and the terminal configuresa bandwidth part having a 60 kHz subcarrier spacing in the terminal, theterminal may ignore the configuration of the bandwidth part having a 60kHz subcarrier spacing.

Method 420 and Method 426 may be applied on a bandwidth part basis. Thatis, when a plurality of downlink bandwidth parts or a plurality ofuplink bandwidth parts are configured in the terminal, a semi-staticslot format having a reference subcarrier spacing identical to asubcarrier spacing configured in each of the bandwidth parts may beapplied to the corresponding bandwidth part. For example, whensemi-static slot formats having reference subcarrier spacings of 15 kHzand 30 kHz, a downlink bandwidth part having a subcarrier spacing of 15kHz, and a downlink bandwidth part having a subcarrier spacing of 30 kHzare configured in the terminal, the terminal may apply the semi-staticslot format having a reference subcarrier interval of 15 kHz to thedownlink bandwidth part having a subcarrier spacing of 15 kHz, and thesemi-static slot format having a reference subcarrier spacing of 30 kHzto the downlink bandwidth part having a subcarrier spacing of 30 kHz.

Meanwhile, when a plurality of downlink bandwidth parts or a pluralityof uplink bandwidth parts are configured in the terminal, onesemi-static slot format having a specific reference subcarrier spacingmay be applied to the plurality of bandwidth parts. This method may bereferred to as ‘Method 427’. For example, when semi-static slot formatshaving reference subcarrier spacings of 15 kHz and 30 kHz, a downlinkbandwidth part having a subcarrier spacing of 15 kHz, and a downlinkbandwidth part having a subcarrier spacing of 30 kHz are configured inthe terminal, the terminal may apply the semi-static slot format havinga reference subcarrier spacing of 15 kHz to both the downlink bandwidthparts having sub-carrier spacings of 15 kHz and 30 kHz.

In Method 427, a criterion by which the terminal determines a referencesubcarrier spacing that is commonly applied to one or more bandwidthparts may be predefined in the specification. For example, the terminalmay determine the smallest subcarrier spacing (hereinafter referred toas ‘Δfmin’) among the subcarrier spacing(s) of the bandwidth part(s)configured by the base station as the reference subcarrier spacing. Whena semi-static slot format having a reference subcarrier spacingidentical to Δfmin is not configured in the terminal, the terminal mayapply a semi-static slot format having the greatest subcarrier spacingamong reference subcarrier spacing(s) smaller than Δfmin to thebandwidth part(s). When the above-described rule is used and thesubcarrier spacing of the bandwidth part is greater than the referencesubcarrier spacing, the terminal may obtain the slot format of thebandwidth part by using the method described with reference to FIG. 6 .

Alternatively, the terminal may apply the semi-static slot format havingthe greatest reference subcarrier spacing among the reference subcarrierspacing not larger than the subcarrier spacing of the bandwidth part tothe corresponding bandwidth part. This method may be referred to as‘Method 428’. For example, when semi-static slot formats havingreference subcarrier spacings of 15 kHz and 30 kHz, and downlinkbandwidth parts having subcarrier spacings of 15 kHz, 30 kHz, and 60 kHzare configured in the terminal, according to Method 408, the terminalmay apply the semi-static slot format having a reference subcarrierinterval of 15 kHz to the downlink bandwidth part having a subcarrierspacing of 15 kHz, and the semi-static slot format having a referencesubcarrier spacing of 30 kHz to the downlink bandwidth parts havingsubcarrier spacings of 30 kHz and 60 kHz.

When a plurality of semi-static slot formats having different referencesubcarrier spacings are configured in the terminal by Method 420, thetransmission directions of symbols according to the semi-static slotformat may be aligned in the time domain between the referencesubcarrier spacings. This method may be referred to as ‘Method 421’.Alternatively, each of the semi-static slot formats may be configuredindependently of one another, and the transmission directions of thesymbols according to the semi-static slot format may not be aligned inthe time domain. This method may be referred to as ‘Method 422’. WhenMethod 422 is used, a high degree of freedom in the configurability maybe provided, however, cross-link interference may be caused between thebandwidth parts having different subcarrier spacings in the same cell.On the other hand, when Method 421 is used, cross-link interference inthe same cell may be suppressed.

When Method 422 is used, repetition periods of the plurality ofsemi-static slot formats may be the same or different. On the otherhand, when Method 421 is used, it may be desirable that the repetitionperiods of the plurality of semi-static slot formats are configured tobe the same.

FIG. 9A is a conceptual diagram illustrating a first embodiment of asemi-static slot format according to Method 421, FIG. 9B is a conceptualdiagram illustrating a second embodiment of a semi-static slot formataccording to Method 421, and FIG. 9C is a conceptual diagramillustrating a third embodiment of a semi-static slot format accordingto Method 421.

Referring to FIGS. 9A to 9C, the base station may configure asemi-static slot format having a reference subcarrier spacing of 15 kHz(hereinafter referred to as a ‘first slot format’) and a semi-staticslot format having a reference subcarrier spacing of 30 kHz (hereinafterreferred to as a ‘second slot format’). The repetition period of thefirst slot format and the second slot format may be 1 ms.

In the embodiment of FIG. 9A, the transmission direction of the firstslot format in the time domain may be the same as the transmissiondirection of the second slot format. That is, the transmission directionof one symbol of the first slot format may be the same as thetransmission direction of the two symbols of the second slot formatcorresponding to one symbol of the first slot format. This method may bereferred to as ‘Method 423’.

On the other hand, in the embodiment of FIG. 9B and the embodiment ofFIG. 9C, there may be a duration in which the transmission direction ofthe first slot format does not coincide with the transmission directionof the second slot format in the time domain. For example, in theembodiment of FIG. 9B, the eighth symbol of the first slot format maycorrespond to ‘downlink symbol and unknown symbol’ of the second slotformat, and the eleventh symbol of the first slot format may correspondto ‘unknown symbol and uplink symbol’ of the second slot format.

That is, the unknown symbol of the first slot format may be aligned withthe ‘downlink symbol and unknown symbol’ or ‘unknown symbol and uplinksymbol’ of the second slot format. This method may be referred to as‘Method 424’, and Method 424 may be similar to Method 411 describedabove. When the reference subcarrier spacing of the first slot format isfour times or more the reference subcarrier spacing of the second slotformat or the reference subcarrier spacing of the second slot format isfour times or more the reference subcarrier spacing of the first slotformat, the unknown symbol of the slot format having a relatively smallreference subcarrier spacing may correspond to all of the downlinksymbol, unknown symbol, and uplink symbol of the slot format having arelatively large reference subcarrier spacing.

As another example, in the embodiment of FIG. 9C, the seventh symbol ofthe first slot format may correspond to the ‘downlink symbol and unknownsymbol’ of the second slot format, and the twelfth symbol of the firstslot format may correspond to the ‘unknown symbol and uplink symbol’ ofthe second slot format. That is, the downlink symbol of the first slotformat may be aligned with the ‘downlink symbol and unknown symbol’ ofthe second slot format, the uplink symbol of the first slot format maybe aligned with the ‘unknown symbol and uplink symbol’ of the secondslot format. This method may be referred to as ‘Method 425’, and Method425 may be similar to Method 412.

The embodiments of FIGS. 9A to 9C may be applied to the first slotformat and the second slot format having various reference subcarrierspacings. Also, Methods 423 to 425 may be used in combination. Forexample, when Method 424 is combined with Method 425, a specificdownlink symbol of the first slot format may correspond to the ‘downlinksymbol and unknown symbol’ of the second slot formation, and a specificunknown symbol of the first slot format may correspond to the ‘unknownsymbol and uplink symbol’ of the second slot format.

When a common repetition period is applied to a plurality of semi-staticslot formats in Method 420 and the detailed methods of Method 420, theuse of a specific repetition period may be restricted. For example, arepetition period (e.g., 0.625 ms, 1.25 ms, 2.5 ms) that is applied onlyto a specific reference subcarrier spacing may not be used as a commonrepetition period for a plurality of semi-static slot formats.

In a fourth method for solving the problem described with reference toFIG. 6 , it may be allowed that a subcarrier spacing of a bandwidth partis configured to be smaller than a reference subcarrier spacing of asemi-static slot format, and it may be expected that a collision oftransmission directions according to a semi-static slot format does notoccur in each of symbols of the bandwidth part. This method may bereferred to as ‘Method 430’. Regardless of a relationship between thesubcarrier spacing of the bandwidth part and the reference subcarrierspacing, the base station may appropriately configure a pattern of thesemi-static slot format to avoid the collision of transmissiondirections. The terminal may expect that the collision of transmissiondirections does not occur even when any bandwidth part is activated.

The effects of the above-described methods may occur when a CP typeapplied to the semi-static slot format and a CP type configured in thebandwidth part are the same. The CP type may be classified into a normalCP and an extended CP. On the other hand, when the CP type applied tothe semi-static slot format is different from the CP type configured inthe bandwidth part, the same effect as described above may not beappreciated because the symbols having different subcarrier spacings arenot aligned with each other in the time domain. For example, when anormal CP is applied to the semi-static slot format and an extended CPis configured in the bandwidth part, the above-described methods shouldbe used in a modified manner, and the above-described effects may notoccur.

Therefore, when it is desired to use both a normal CP and an extended CPin the bandwidth part, it may be preferable that both a normal CP and anextended CP are configured to be applicable to the semi-static slotformat. For this, the configuration information of the semi-static slotformat may include a CP type. The CP type may indicate a normal CP or anextended CP used for configuring the bandwidth part. For example, the CPtype may be included in the configuration information of thecell-specific semi-static slot format. In this case, the CP type may betransmitted to the terminal as system information. When theconfiguration information of the semi-static slot format includes the CPtype, Method 420 and the detailed methods of Method 420 may be appliedto a plurality of semi-static slot formats having the same CP type.

The above-described methods may be applied not only when the referencesubcarrier spacing of the semi-static slot format is different from thesubcarrier spacing of the bandwidth part, but also when the referencesubcarrier spacing of the dynamic slot format is different from thesubcarrier spacing of the bandwidth part. For example, when a slotformat indicated by the SFI is identified, the terminal may apply theslot format indicated by the SFI to a bandwidth part having a subcarrierspacing other than a reference subcarrier spacing of the slot formatindicated by the SFI according to the above-described methods.

Dynamic Switching of Bandwidth Part

When a plurality of downlink bandwidth parts or a plurality of uplinkbandwidth parts are configured in the terminal, the base station maytransmit a DCI including a field (e.g., bandwidth part indicator field)indicating an index of an active bandwidth part to the terminal. Theterminal may transmit or receive a data channel (e.g., PDSCH or PUSCH)scheduled by the DCI in the bandwidth part indicated by the bandwidthpart indicator field of the DCI. According to this, the bandwidth partthrough which the DCI is transmitted may be an active bandwidth partbefore switching, and the bandwidth part indicated by the DCI may be anactive bandwidth part after switching. In the following embodiments,when a bandwidth part is switched, the active bandwidth part beforeswitching may be referred to as a ‘first bandwidth part’, and the activebandwidth part after switching may be referred to as a ‘second bandwidthpart’. The terminal may perform switching of the bandwidth part betweena reception end point of the DCI in the first bandwidth part and atransmission and reception starting point of a data channel in thesecond bandwidth part (e.g., a reception starting point of the PDSCH ora transmission starting point of the PUSCH).

FIG. 10 is a conceptual diagram illustrating a first embodiment of adynamic switching method of a bandwidth part in a communication system.

Referring to FIG. 10 , a base station may transmit a DCI to a terminalthrough a PDCCH in a first bandwidth part. The DCI may includescheduling information of a data channel (e.g., PDSCH or PUSCH), abandwidth part indicator field, and the like. The bandwidth partindicator field may include an index of a second bandwidth part. Theterminal may receive the DCI in the first bandwidth part, and maytransmit or receive the data channel (e.g., PDSCH or PUSCH) scheduled bythe DCI in the second bandwidth part indicated by the bandwidth partindicator field of the DCI. The terminal may interpret schedulinginformation of the DCI (e.g., frequency domain resource allocationinformation, time domain resource allocation information, transmissionconfiguration information (TCI) state, etc.) based on the configurationinformation of the second bandwidth part (e.g., subcarrier spacing, CPlength, beam information, etc.).

In order to switch from the first bandwidth part to the second bandwidthpart, it may take some time at the terminal. First, since the terminalshould process the PDCCH in order to obtain the DCI (e.g., the DCIincluding the bandwidth part indicator field) instructing the bandwidthpart switching, a PDCCH processing delay time T1 may be considered in abandwidth part switching time. The PDCCH processing delay time T1 may bea time interval from a reception ending point of the PDCCH to aprocessing completion point of the PDCCH. Also, T1 may include the PDCCHprocessing delay time as well as a driving time of other basebanddevices. When the DCI is obtained, a time for the terminal to retune aradio frequency (RF) bandwidth to the bandwidth part indicated by thebandwidth part indicator field of the DCI may be needed. The RF retuningtime T2 may be several micro seconds to several hundred micro secondsdepending on a change ratio of the RF bandwidth and whether a center ofthe RF bandwidth is moved or not. Also, T2 may include the RF tuningtime as well as a driving time of other RF devices (e.g., automatic gaincontrol (AGC)).

When instructing the bandwidth part switching, the base station mayschedule the data channel so that the terminal can acquire T1 and T2.When a time interval from the reception ending point of the PDCCHincluding the DCI to the transmission and reception starting point(e.g., reception stating point of the PDSCH or transmission startingpoint of the PUSCH) of the data channel scheduled by the DCI is T3, thebase station may schedule the data channel so that T3 is equal to orgreater than ‘T1+T2’. Alternatively, at least one of T1 and T2 may bedefined in the specification as the capability of the terminal (e.g.,the terminal's requirements). For example, in Method 500, the ‘T1+T2’may be predefined in the specification as the capability of theterminal, and the terminal may report the ‘T1+T2’ to the base station.In Method 501, each of T1 and T2 may be defined in the specification asthe capability of the terminal, and the terminal may report each of T1and T2 to the base station. In Method 502, T2 may be defined in thespecification as the capability of the terminal, and the terminal mayreport T2 to the base station.

The terminal may adjust the RF bandwidth in an arbitrary time durationin ‘T3−T1’. That is, the terminal may adjust the RF bandwidth in anarbitrary time interval between the acquisition time of the DCI and thetransmission and reception starting time of the data channel scheduledby the DCI. In this case, it is difficult for the base station to knowthe duration in which the terminal adjusts the RF bandwidth, and theoperation of the terminal is unclear at T3 or ‘T3−T1’, and thus the useof the corresponding duration (e.g., T3 or ‘T3−T1’) may be restricted.In particular, when T3 is greater than ‘ T1+T2’ (e.g., when cross-slotscheduling is performed), the previously described problem may arise.

In order to solve the above-described problem, the RF transitionduration of the terminal may be defined in advance in the specification.Alternatively, the base station may configure the RF transition durationin the terminal. This method may be referred to as ‘Method 510’. The RFtransition duration may be configured to be equal to or greater than T2,and the terminal may adjust the RF bandwidth within the RF transitionduration. Also, the terminal may not perform other operations inaddition to the RF bandwidth adjustment operation within the RFtransition duration. For example, the terminal may not transmit orreceive any signal within the RF transition duration. The terminal mayperform a normal transmission and reception operation in a time durationother than the RF transition duration. Method 501 or 502 may be used toensure that the RF transition duration is set to be equal to or greaterthan T2 in Method 510. For example, the base station may identify T2 ofthe terminal according to Method 501 or 502, and may configure the RFtransition duration so that the RF transmission duration is equal to orgreater than the identified T2.

The RF transition duration for the bandwidth part switching may becomposed of N1 consecutive symbols. N1 may be a natural number. Thelength of the RF transition duration may be expressed as N1. Thesymbol(s) constituting the RF transition duration may follow a specificnumerology (e.g., subcarrier spacing, CP length). Meanwhile, since theRF transition duration exists within T3 in the bandwidth part switchingmethod described above, the location of the RF transition duration maybe configured based on the time domain location of the DCI (e.g., PDCCHincluding the DCI) transmitted in the first bandwidth part or the timedomain location of the data channel (e.g., PDSCH or PUSCH) transmittedin the second bandwidth part as a reference. The RF transition durationmay be configured as follows.

FIG. 11A is a conceptual diagram illustrating a first embodiment of anRF transition duration in a communication system, FIG. 11B is aconceptual diagram illustrating a second embodiment of an RF transitionduration in a communication system, and FIG. 11C is a conceptual diagramillustrating a third embodiment of an RF transition duration in acommunication system.

Referring to FIG. 11A, an offset O1 between a starting point of the RFtransition duration and an ending point of the PDCCH in the firstbandwidth part may be defined. The base station may inform the terminalof the offset O1. The RF transition duration may be composed of N1consecutive symbols, and the offset O1 may be composed of N2 consecutivesymbols. Each of N1 and N2 may be a natural number.

Referring to FIG. 11B, an offset O2 between an ending point of the RFtransition duration and a starting point of the data channel in thesecond bandwidth part may be defined. The base station may inform theterminal of the offset O2. The RF transition duration may be composed ofN1 consecutive symbols, and the offset O2 may be composed of N3consecutive symbols. Each of N1 and N3 may be a natural number.

Referring to FIG. 11C, when the PDCCH processing delay time T1 isdefined, an offset O3 may be defined between the starting point of theRF transition duration and an ending point of the PDCCH processing delaytime T1 The base station may inform the terminal of the offset O3. TheRF transition duration may be composed of N1 consecutive symbols, andthe offset O3 may be composed of N4 consecutive symbols. Each of N1 andN4 may be a natural number.

The base station may transmit configuration information of the RFtransition duration for the bandwidth part switching to the terminalthrough signaling. For example, a higher layer signaling (e.g., RRCsignaling, MAC signaling) or a physical layer signaling (e.g., DCIindicating switching of the bandwidth part) may be used for transmissionof the configuration information of the RF transition duration. Thelength (e.g., N1) of the RF transition duration may be determined by T2(i.e., the RF retuning time). The length of the RF transition durationmay preferably be configured semi-statically by the higher layersignaling.

On the other hand, the offsets (e.g., O1, O2, O3) for indicating thelocation of the RF transition duration may be transmitted to theterminal through a higher layer signaling or a physical layer signaling.When the offsets (e.g., O1, O2, O3) are dynamically indicated by thephysical layer signaling, an efficiency of time resource usage may beincreased, but a signaling overhead may increase. Alternatively, the RFtransition duration may be configured by a combination of the higherlayer signaling and the physical layer signaling. For example, candidatevalue(s) of the configuration information (e.g., length, offset,numerology, etc.) of the RF transition duration may be preconfigured inthe terminal by the higher layer signaling, and one of the candidatevalue(s) of the configuration information may be indicated dynamicallyby the physical layer signaling.

On the other hand, since the bandwidth part switching method may varydepending on the configuration of the bandwidth part, a plurality of T2may be used. For example, when a change of an RF filter center isrequired for switching from the first bandwidth part to the secondbandwidth part, a relatively large T2 may be used. On the other hand,when a change of an RF filter center is not required, a relatively smallT2 may be used. When a plurality of T2 are used, a plurality of RFtransition durations may be configured. In this case, the RF transitionduration may be configured for each T2. Alternatively, the RF transitionduration may be configured for each of the first bandwidth part, thesecond bandwidth part, and a combination of the first bandwidth part andthe second bandwidth part. When the RF transition duration is configuredfor each T2, the terminal may perform the bandwidth part switchingaccording to the RF transition duration corresponding to T2 after the T2used for the bandwidth part switching is determined.

Meanwhile, a numerology of the first bandwidth part may be differentfrom a numerology of the second bandwidth part. Each of the length andoffsets (e.g., O1, O2, O3) of the RF transition duration may be definedbased on the numerology of a predetermined bandwidth part among thefirst bandwidth part and the second bandwidth part. For example, whenthe RF transition duration is configured according to the embodiment ofFIG. 11A or the embodiment of FIG. 11C, each of N1, N2, and N4 may bedetermined based on the numerology of the first bandwidth part (e.g.,symbol length, subcarrier spacing).

Alternatively, when the RF transition duration is configured accordingto the embodiment of FIG. 11B, each of N1 and N3 may be determined basedon the numerology of the second bandwidth part (e.g., symbol length,subcarrier spacing). Alternatively, the RF transition duration may beconfigured based on a smaller subcarrier spacing or a greater subcarrierspacing among a subcarrier spacing of the first bandwidth part and asubcarrier spacing of the second bandwidth part. Alternatively, the RFtransition duration may be configured based on a reference numerology.The reference numerology may be configured regardless of the numerologyof the first bandwidth part and the numerology of the second bandwidthpart. The reference numerology may be included in the configurationinformation of the RF transition duration.

Determination of Dynamic Slot Format

The base station may dynamically inform the terminal of a slot formatusing a DCI. The base station may inform the terminal of candidate(s) ofthe slot formats that can be indicated by an SFI through RRC signaling.Then, the base station may transmit a DCI including an SFI indicatingone of the candidate slot format(s) to the terminal. A set of slotformat candidate(s) may be configured per cell or per carrier, and maybe applied in common to all bandwidth parts within a cell. A subcarrierspacing (e.g., reference subcarrier spacing) used as a reference forinterpreting the slot format candidate(s) may be configured in theterminal through RRC signaling and may be configured for each cell oreach carrier. The same reference subcarrier spacing may be applied toall slot format candidate(s) configured by RRC signaling within a cell.

For example, the base station may configure 4 slot format candidates inthe terminal via RRC signaling. Each of the 4 slot format candidates maybe [DDDDDDDDDDDDDD], [DDDDDDDDDDXXUU], [DDDDDDDXXUUUU], or[DDDDDXXUUUUUU]. Each of the 4 slot format candidates may be a formatfor one slot. In the slot format candidate, AD′ may be a downlinksymbol, ‘X’ may be an unknown symbol, and ‘II’ may be an uplink symbol.A reference subcarrier spacing (e.g., 15 kHz) of the SFI may beconfigured with 4 slot format candidates. In this case, the length ofone slot may be 1 ms. The base station may transmit a DCI including anSFI indicating one of the 4 slot format candidates to the terminal. Theterminal receiving the DCI may identify the slot format based on the SFIincluded in the DCI, and may apply the identified slot format to theslot in which the DCI is received.

On the other hand, a PDCCH monitoring occasion for receiving the SFI(e.g., the DCI including the SFI) of the terminal may be configured foreach bandwidth part. Specifically, a DCI format used for transmission ofthe SFI may be transmitted through a PDCCH common search space, and amonitoring period of the PDCCH common search space for the transmissionof the SFI may be configured for each downlink bandwidth part. The PDCCHmonitoring occasion for receiving the SFI reception (hereinafterreferred to as a ‘SFI monitoring occasion’) may be configured asfollows.

FIG. 12 is a conceptual diagram illustrating a first embodiment of anSFI monitoring occasion in a communication system.

Referring to FIG. 12 , in a first bandwidth part, an SFI monitoringoccasion may be configured differently from an SFI monitoring occasionin a second bandwidth part. For example, a period of the SFI monitoringoccasion in the first bandwidth part may be 1 slot, and a period of theSFI monitoring occasion in the second bandwidth part may be 2 slots. Thebase station may configure the period of the SFI monitoring occasion ofeach of the bandwidth parts to the terminal. In this case, an SFIreceived in the first bandwidth part may indicate a format for one slot,and an SFI received in the second bandwidth part may indicate formatsfor the 2 slots. Here, a numerology of the first bandwidth part may beassumed to be the same as a numerology of the second bandwidth part.

The terminal may be instructed to perform switching from the firstbandwidth part to the second bandwidth part. When the terminal isinstructed to switch from the first bandwidth part to the secondbandwidth part, the terminal may receive a DCI through the firstbandwidth part of a slot #n, and may identify scheduling informationincluded in the DCI. The scheduling information may be schedulinginformation for a data channel (e.g., PDSCH or PUSCH) transmitted in thesecond bandwidth part. For example, a data channel may be scheduled by aDCI in each of the slots #n and #(n+1). That is, a data channel may bescheduled in D1 in the slot #n and a data channel may be scheduled in D2in the slot #(n+1).

Before performing the switching operation of the bandwidth part, theterminal may successfully receive the SFI in the first bandwidth part ofthe slot #n. In this case, the SFI may be applied to not only the firstbandwidth part but also the second bandwidth part of the slot #n. Thus,after switching from the first bandwidth part to the second bandwidthpart, regardless of the sameness between the numerology of the firstbandwidth part and the numerology of the second bandwidth part, the slotformat indicated by the SFI received in the first bandwidth part of theslot #1 may be applied to the second bandwidth portion of the slot #n.When the numerology of the first bandwidth part differs from thenumerology of the second bandwidth part, the terminal may convert thenumerology by the method described with reference to FIG. 7 or the likeso as to apply the slot format indicated by the SFI received in thefirst bandwidth part of the slot #n to the second bandwidth part of thslot #n.

However, in the present embodiment, there is no SFI monitoring occasionin which the SFI for the slot #(n+1) can be transmitted due to thebandwidth part switching. Therefore, it may be difficult for theterminal to acquire the dynamic slot format for the slot #(n+1) throughthe conventional method. In the following embodiments, terminaloperations will be described in a duration (hereinafter referred to as a‘first duration’) for which a slot format is not indicated by an SFI dueto the bandwidth part switching.

When a semi-static slot format is configured in the terminal, theterminal may assume downlink transmission in a downlink duration anduplink transmission in an uplink duration based on the semi-static slotformat. In this case, the terminal operation may be further defined in aduration configured as unknown by the semi-static slot format in thefirst duration. On the other hand, when the semi-static slot format isnot configured in the terminal, the terminal may regard all the symbolsconstituting the first duration as unknown symbols. In this case, theterminal operation may be defined throughout the first duration. In thefollowing embodiments, each of a ‘semi-static unknown symbol’ and a‘semi-static unknown duration’ in the first duration may indicatesymbols regarded as unknown symbols when a semi-static slot format isnot configured in the terminal or a duration configured as an unknownduration by a semi-static slot format.

In Method 600, the terminal may not perform any operation in thesemi-static unknown symbol of the first duration. The terminal may nottransmit or receive a data channel (e.g., PDSCH or PUSCH), and may notperform a transmission or measurement operation of a reference signal inthe semi-static unknown symbol of the first duration. In the embodimentof FIG. 12 , when D2 is composed of semi-static unknown symbols, theterminal may not transmit or receive a data channel in D2. Also, theterminal may not expect a data channel to be scheduled in the firstduration. Therefore, in the present embodiment, the terminal maytransmit or receive a data channels only in D1.

In Method 601, the terminal may regard an SFI monitoring occasion as notconfigured in the first duration, and may perform the same operation asa case where the SFI monitoring occasion is not configured. That is,although the SFI monitoring occasion for the first bandwidth part andthe second bandwidth part are configured, the terminal may regard theSFI monitoring occasion in the first duration as not configured. In theembodiment of FIG. 12 , when D2 does not include semi-static uplinksymbols, the terminal may receive a PDSCH in slot #(n+1). Alternatively,the terminal may monitor a PDCCH in the semi-static unknown symbol inthe first duration. Alternatively, the terminal may perform transmissionor reception of a semi-static or semi-persistent reference signalconfigured by a higher layer signaling in the semi-static unknown symbolin the first duration.

On the other hand, although the SFI monitoring occasion is configured inthe terminal, the terminal may not receive an SFI in a specific SFImonitoring occasion (e.g., a PDCCH monitoring occasion in a specificslot). In Method 602, although an SFI monitoring occasion is notconfigured in the terminal in the first duration, the terminal mayregard an SFI monitoring occasion as configured in the first duration,and may perform the same operation as in the case of not receiving theSFI even when the SFI monitoring occasion is configured. For example,the terminal may perform an operation according to Method 601 for aPDCCH monitoring or a data channel dynamically scheduled in thesemi-static unknown symbol in the first duration. Alternatively, theterminal may not transmit a semi-static or semi-persistent referencesignal configured by a higher layer signaling in the semi-static unknownsymbol in the first duration.

In Method 603, the terminal may apply a format of a previous slot to thefirst duration. In the embodiment of FIG. 12 , the terminal may applythe SFI received in the slot #n of the first bandwidth part to the slot#(n+1) (e.g., the first duration in the slot #(n+1)). That is, theterminal may repeatedly apply the SFI received in the first bandwidthpart until the next SFI monitoring occasion in the second bandwidthpart. When the SFI indicates a format for a plurality of slots, thecorresponding SFI may be repeatedly applied in a wrap-around mannerbefore the next SFI monitoring occasion.

In Method 604, the base station may generate an SFI (e.g., an SFItransmitted before switching of the bandwidth part) includingconfiguration information of a slot format of the first duration, andtransmit the generated SFI to the terminal. In the embodiment of FIG. 12, the terminal may identify the configuration information of the slotformat of the first duration based on the SFI received in the slot #n ofthe first bandwidth part.

In Method 605, the base station may generate a DCI (e.g., DCI indicatingswitching of the bandwidth part) including configuration information ofa slot format of the first duration, and transmit the generated DCI tothe terminal. In the embodiment of FIG. 12 , the terminal may identifythe configuration information of the slot format of the first durationbased on the DCI received in the slot #n of the first bandwidth part.

Alternatively, a two-step DCI may be used in Method 605. The terminalmay obtain scheduling information of a data channel by receiving a firstDCI and a second DCI. Here, the first DCI and the second DCI may betransmitted through a PDCCH search space. Alternatively, the first DCImay be transmitted through the PDCCH search space, and the second DCImay be transmitted through a part of a resource region in which the datachannel is scheduled. In this case, the first DCI may include abandwidth part indicator field.

When the switching of the bandwidth part is triggered by the first DCI,the second DCI may be transmitted in the switched bandwidth part (e.g.,the second bandwidth part). In this case, the base station may transmitthe second DCI including the configuration information of the slotformat of the first section to the terminal. This method may be referredto as ‘Method 606’. Since a payload size of the second DCI is not solarge compared to a payload size of the first DCI, the configurationinformation of the slot format of the first duration may be included inthe second DCI rather than the first DCI transmitted through the PDCCHsearch space. When the first duration occurs in the switching of thebandwidth part, the terminal may assume that the configurationinformation of the slot format of the first duration is included in thesecond DCI. Alternatively, the first DCI may include an indicatorindicating whether the configuration information of the slot format ofthe first duration is included in the second DCI.

Even when any of the above-described methods is used, the terminal maydetermine whether or not a data channel scheduled by the DCI (e.g., theDCI including the bandwidth part indicator field) instructing to switchthe bandwidth part is transmitted based on the same criterion as that ofthe conventional method. For example, when a transmission direction of adata channel does not collide with a transmission direction according tothe semi-static slot format in the slot #(n+1) of FIG. 12 , the terminalmay transmit or receive the corresponding data channel.

Meanwhile, as another method for solving the above-described problem,the terminal may use a common SFI monitoring occasion and a commonoffset in all bandwidth parts in the same cell. This method may bereferred to as ‘Method 610’. The terminal may expect that a period andan offset (e.g., slot offset) of the PDCCH monitoring occasion for SFIreception are configured to be equal in all downlink bandwidth partswithin the same cell. According to Method 610, the terminal can monitoran SFI at a specific point regardless of the active bandwidth part, sothat a duration (e.g., the first duration) for which a slot format isnot indicated may not occur.

Method 610 may be applied to bandwidth parts having the same subcarrierspacing. However, even when the bandwidth parts have differentsubcarrier spacings, monitoring periods and offsets of search spaces forthe DCI format 2-0 may be appropriately adjusted, so that the periodsand offsets of the SFI monitoring occasions of the terminal areconfigured to be the same in the bandwidth parts having differentsubcarrier spacings. For example, when downlink bandwidth parts havingsubcarrier spacings of 15 kHz and 30 kHz are configured in the terminal,the terminal may monitor an SFI in each S-th slot in the downlinkbandwidth part having a subcarrier spacing of 15 kHz, and may monitor anSFI in each (2×S)-th slot in the downlink bandwidth part having asubcarrier spacing of 30 kHz. In this case, an absolute value of theperiod of the SFI monitoring occasion in the downlink bandwidth parthaving the subcarrier spacing of 15 kHz may be equal to an absolutevalue of the period of the SFI monitoring occasion in the downlinkbandwidth part having the subcarrier spacing of 30 kHz. Method 610 maybe applied to the embodiment of FIG. 13 described below.

FIG. 13 is a conceptual diagram illustrating a second embodiment of anSFI monitoring occasion in a communication system.

Referring to FIG. 13 , in a first bandwidth part, an SFI monitoringoccasion may be configured differently from an SFI monitoring occasionin a second bandwidth part. For example, a period of the SFI monitoringoccasion in the first bandwidth part may be 2 slots, and a period of theSFI monitoring occasion in the second bandwidth part may be 1 slot. Inthis case, an SFI received by the terminal in the first bandwidth partmay indicate the slot format for 2 slots, and an SFI received by theterminal in the second bandwidth part may indicate the slot format for 1slot. Therefore, the terminal may receive a plurality of SFIs indicatingthe format of the slot #(n+1). For example, the terminal may identifythe format of the slot #(n+1) based on the SFI (hereinafter referred toas a ‘first SFI’) received through the first bandwidth part in the slot#n, and identify the format of the slot #(n+1) based on the SFI(hereinafter referred to as a ‘second SFI’) received through the secondbandwidth part in the slot #(n+1). A terminal operation may be definedin a duration for which a slot format is indicated by a plurality ofSFIs (hereinafter referred to as a ‘second duration’).

When the SFI monitoring occasion is configured to the terminal asdescribed above, the terminal may expect to receive one SFI indicatingthe slot format of the second duration. This method may be referred toas ‘Method 620’. Therefore, the base station may transmit one SFI amongthe first SFI and the second SFI to the terminal. The format of the slot#n may not be indicated when the second SFI is transmitted instead ofthe first SFI. Therefore, the base station preferably transmits thefirst SFI instead of the second SFI. When the SFI is selectivelytransmitted, the base station may transmit the SFI in the bandwidth partwhose period of the SFI monitoring occasion is relatively long. In thiscase, the terminal may expect to receive the SFI in the SFI monitoringoccasion with a relatively long period among the SFI monitoringoperations.

Alternatively, the terminal may expect to receive one or more SFIsindicating the slot format of the second duration. When the slot formatof the second duration is indicated by a plurality of SFIs, the terminalmay assume that the slot format indicated by the plurality of SFIs isthe same. This method may be referred to as ‘Method 621’. When Method621 is used, the terminal may not perform a monitoring operation forreception of the second SFI when the first SFI is successfully received.However, if a false alarm of the first SFI occurs, it may be helpful forthe terminal to perform a monitoring operation of the second SFI.

On the other hand, the base station may update the format of the slot#(n+1) through the SFI of the slot #(n+1) even when the SFI istransmitted in the slot #n. In this case, the terminal may expect toreceive a plurality of SFIs for the second duration, and apply thelatest SFI to the second duration when the plurality of SFIs arereceived. This method may be referred to as ‘Method 622’. However, whenthe terminal successfully receives the first SFI but fails to receivethe second SFI, the understanding of the base station and the terminalfor the slot format of the second duration may be different.

Alternatively, the terminal may not apply the configuration of thedynamic slot format in a predetermined time duration when switching thebandwidth part. This method may be referred to as ‘Method 630’. That is,the terminal may regard the predetermined time duration as astabilization period according to the switching of the bandwidth part,and may not perform an operation that may cause ambiguity within thepredetermined time duration. For example, the terminal may ignore SFIsreceived within the certain time duration. The length of thepredetermined time duration to which the SFI is not applied may bepredefined in the specification. Alternatively, the base station mayconfigure the length of the predetermined time duration in the terminal.The location of the predetermined time duration may be derived from areference time point. For example, the location of the predeterminedtime duration to which the SFI is not applied may be determined based ona reception point (e.g., symbol or slot) of the DCI indicating theswitching of the bandwidth part or an activation point (e.g., symbol orslot) of the second bandwidth part. Method 630 may be used foroperations other than the operations configuring the slot format. Forexample, Method 630 may be used to define terminal operations accordingto a preemption indicator (PI) described below.

FIG. 14 is a conceptual diagram illustrating a first embodiment of a PImonitoring occasion in a communication system.

Referring to FIG. 14 , a PDCCH monitoring occasion (hereinafter referredto as a ‘PI monitoring occasion’) for PI reception may be configured foreach bandwidth part. Different PI monitoring occasions may berespectively configured in the terminal in the first bandwidth part andthe second bandwidth part. For example, a period of the PI monitoringoccasion in the first bandwidth part may be set to 2 slots, and a periodof the PI monitoring occasion in the second bandwidth part may be set to1 slot. A time duration for which the terminal applies the PI may be onePI monitoring occasion just before the reception of the PI. That is, thetime duration for which the PI is applied may be from the first symbolin the PI monitoring occasion immediately before the reception of the PIto the previous symbol of the first symbol in the PI monitoring occasionin which the PI is received. The terminal may apply the PI received inthe slot #(n−1) of the first bandwidth part to the slots #(n−3) and#(n−2), apply the PI received in the slot #(n+1) of the second bandwidthpart to the slot #n, and apply the PI received in the slot #(n+2) of thesecond bandwidth part to the slot #(n+1).

The terminal may perform the switching operation of the bandwidth partaccording to the DCI received in the slot #n. In this case, thebandwidth part of the terminal may be switched from the first bandwidthpart to the second bandwidth part. After the bandwidth part is switched,the terminal may receive the PI in the slot #(n+1). In this case, it maybe necessary to define a time duration to which the PI received in theslot #(n+1) is applied. Since the PI is received in the second bandwidthpart, the time duration to which the PI is applied may be determinedbased on the period of the PI monitoring occasion in the secondbandwidth part. For example, the PI received in the slot #(n+1) may beapplied to the slot #n. However, when a preemption occurs in the slot#(n−1), the base station may not inform the terminal that the preemptionoccurs in the slot #(n−1). To solve this problem, the PI received inslot #(n+1) may be applied to the slots #(n−1) and #n. In this case, thebase station may inform the terminal that a preemption occurs in theslot #(n−1) using the PI transmitted in the slot #(n+1).

Timer-Based Bandwidth Switching

The terminal may receive the DCI in the first bandwidth part, andidentify that switching from the first bandwidth part to the secondbandwidth part is requested based on a bandwidth part indicator field ofthe DCI. When a timer-based bandwidth part switching method is notsupported at the terminal, the terminal may operate in the secondbandwidth part until receiving a DCI instructing to switch to a thirdbandwidth part other than when a fallback operation is required. Here,the first bandwidth part may be the third bandwidth part. On the otherhand, when the timer-based bandwidth part switching method is supportedby the terminal, the terminal may start a timer used for checking theactivation time of the second bandwidth part, and when the timerexpires, the terminal may perform a deactivation operation of the secondbandwidth part and a switching operation to a default bandwidth part.

One of the bandwidth parts configured in the terminal may be configuredas a default bandwidth part. When the default bandwidth part is notconfigured separately, an initial active bandwidth part may be used asthe default bandwidth part. For example, when the initial activebandwidth part is the first bandwidth part, the first bandwidth part maybe the default bandwidth part. The base station may configure the timerto the terminal. The configuration unit of the timer may be amillisecond or a slot. When the timer is set to 50 ms, the expirationtime of the timer may be 50 ms, and then the timer may be initialized to0 ms. Alternatively, when the timer is set to 50 ms, the expiration timeof the timer may be 0 ms, and then the timer may be initialized to 50ms.

When a DCI that schedules a data channel is received in the secondbandwidth part, the terminal may extend the activation time of thesecond bandwidth part by initializing or extending the timer. Theextension of the timer may mean that the timer is set to another valuethat is different from the initial value. In a FDD-based communicationsystem, the timer may be independently applied to each of an uplinkbandwidth part and a downlink bandwidth part. In a TDD-basedcommunication system, the timer may be applied to a pair of an uplinkbandwidth part and a downlink bandwidth part.

Meanwhile, the terminal may perform a random access procedure forvarious purposes. A terminal operating in the RRC connected state mayalso perform a contention-based or a contention-less random accessprocedure. For example, when there is no physical resource to transmit ascheduling request (SR) or a buffer status report (BSR), the terminalmay perform the contention-based random access procedure by transmittinga PRACH to the base station.

When a PRACH resource is present in the active uplink bandwidth part andthere is a search space for reception of Msg2 and/or Msg4 in the activedownlink bandwidth part, the terminal may perform the random accessprocedure through the active bandwidth part. However, when there is noPRACH resource in the active uplink bandwidth part, the terminal mayswitch the active uplink bandwidth part to an uplink bandwidth part inwhich a PRACH resource is configured. When there is no search space forreception of Msg2 and/or Msg4 in the active downlink bandwidth part, theterminal switch the current active downlink bandwidth part to a downlinkbandwidth part in which a search space for reception of Msg2 and/or Msg4is configured. Alternatively, the terminal may expect that the PDCCHsearch space for reception of Msg2 and/or Msg4 is configured in alldownlink bandwidth parts of the terminal. That is, the terminal mayexpect that all downlink bandwidth parts configured in the terminal arelogically associated with a control resource set (CORESET) including acommon search space for monitoring the DCI format 0-0.

It may happen that switching of the bandwidth part is required while therandom access procedure is performed in the active bandwidth part. Forexample, a case where the timer-based bandwidth part switching issupported and the timer of the active bandwidth part expires aftertransmission of the PRACH may occur. In this case, the terminal maycontinue to perform the random access procedure in the bandwidth part inthe PRACH is transmitted without switching to the default bandwidthpart. This method may be referred to as ‘Method 700’. Alternatively, theterminal may switch the current active bandwidth part to the defaultbandwidth part, and perform a random access procedure in the switcheddefault bandwidth part (e.g., a random access procedure continued fromthe random access procedure performed in the active bandwidth partbefore switching, or a new random access procedure). This method may bereferred to as ‘Method 710’.

When Method 700 is used, a method of initializing or extending the timerfor the active bandwidth part may be used. This method may be referredto as ‘Method 701’. When Msg2, which is a response to the PRACH, is notreceived from the base station, the terminal may retransmit the PRACHthrough another beam or retransmit the PRACH using a higher transmissionpower. When a plurality of PRACHs are transmitted, the base station mayreceive the PRACH that the terminal last transmitted. In this case, thebase station may not know the transmission order of the received PRACH(e.g., preamble) among the plurality of PRACHs transmitted from thePRACH.

In order to ensure that the base station and the terminal assume thesame timer after the transmission and reception of Msg1 is completed,the terminal may initialize or extend the timer every time it transmitsthe PRACH. This method may be referred to as ‘Method 702’. In Method702, the base station may initialize or extend the timer when the PRACHis received. When a plurality of PRACHs are received from the terminal,the base station may initialize or extend the timer each time itreceives the PRACH. The timer used in Method 701 may be configured inthe terminal by the base station. Alternatively, a timer value used inMethod 701 may be the same as the timer value applied to the switchingoperation of the bandwidth part.

In the TDD-based communication system, the method of managing the timeraccording to Method 701 may be applied to a pair of the uplink bandwidthpart and the downlink bandwidth part. When an ID of the uplink bandwidthpart is the same as an ID of the downlink bandwidth part, a common timermay be used in the uplink bandwidth part and the downlink bandwidthpart. In the FDD-based communication system, the timer may be managedindependently in each of the uplink bandwidth part and the downlinkbandwidth part. Alternatively, the timer may only be used in thedownlink bandwidth part. Therefore, in the FDD-based communicationsystem, Method 701 may be applied to one of the uplink bandwidth partand the downlink bandwidth part. For protection of the Msg1 transmissionprocedure, Method 701 may be used only for the uplink bandwidth part.For example, the terminal that transmitted the PRACH may initialize orextend the timer of the uplink bandwidth part in which the PRACH istransmitted. When the timer is not used in the uplink bandwidth part,Method 701 may be applied to the downlink bandwidth part or theTDD-based communication system.

When the active bandwidth part is switched to the default bandwidth partduring the execution of the Msg1 transmission procedure in Method 710,the terminal may perform an Msg1 transmission procedure (e.g., an Msg1transmission procedure continued from the Msg1 transmission procedureperformed in the active bandwidth part before switching or a ‘new Msg1transmission procedure’) in the switched default bandwidth part. Whenthe Msg1 transmission procedure continued from the Msg1 transmissionprocedure performed in the active bandwidth part before switching isperformed, the terminal may proceed with the Msg1 transmission procedurewithout changing a power ramping counter and/or the beam changeinformation after switching of the bandwidth part. According to thismethod, when the channel/beam environment and the PRACH resourceconfiguration in the previous bandwidth part before switching aresimilar to the channel/beam environment and PRACH resource configurationin the switched default bandwidth portion, a time required forsuccessfully transmitting Msg1 may be shortened. On the other hand, whenthe new Msg1 transmission procedure is performed, the terminal mayinitialize the power ramping counter and/or the beam change information,and perform the new Msg1 transmission procedure in the default bandwidthpart. The two methods described above may be used for differentenvironments. In this case, the base station may inform the terminal ofthe method used among the two methods.

Although Method 700, the detailed methods of Method 700, Method 710, andthe detailed methods of Method 710 are described in the environment inwhich the timer-based bandwidth switching is supported, Method 700, thedetailed methods of Method 700, Method 710, and the detailed methods ofMethod 710 may also be applied to the environment in which thetimer-based bandwidth switching is not supported. During the executionof the random access procedure, it may happen that switching of thebandwidth part is required by the instruction of the DCI. In this case,Method 700, the detailed methods of Method 700, Method 710, and thedetailed methods of Method 710 may be used.

The embodiments of the present disclosure may be implemented as programinstructions executable by a variety of computers and recorded on acomputer readable medium. The computer readable medium may include aprogram instruction, a data file, a data structure, or a combinationthereof. The program instructions recorded on the computer readablemedium may be designed and configured specifically for the presentdisclosure or can be publicly known and available to those who areskilled in the field of computer software.

Examples of the computer readable medium may include a hardware devicesuch as ROM, RAM, and flash memory, which are specifically configured tostore and execute the program instructions. Examples of the programinstructions include machine codes made by, for example, a compiler, aswell as high-level language codes executable by a computer, using aninterpreter. The above exemplary hardware device can be configured tooperate as at least one software module in order to perform theembodiments of the present disclosure, and vice versa.

While the embodiments of the present disclosure and their advantageshave been described in detail, it should be understood that variouschanges, substitutions and alterations may be made herein withoutdeparting from the scope of the present disclosure.

1. A method of a terminal, the method comprising: performing a firstrandom access (RA) procedure with a base station in a first bandwidthpart (BWP); receiving information indicating a BWP switching from thebase station while the first RA procedure is performed; determiningwhether the BWP switching is performed; and performing one RA procedureof a RA procedure based on a first manner and a RA procedure based on asecond manner, based on whether the BWP switching is performed, wherein,in the RA procedure based on the first manner, the terminal stops thefirst RA procedure, switches from the first BWP to a second BWP byperforming the BWP switching, and performs a second RA procedure withthe base station in the second BWP, wherein, in the RA procedure basedon the second manner, the terminal ignores an indication of the BWPswitching and continues to perform the first RA procedure in the firstBWP without the BWP switching.
 2. The method of claim 1, wherein, in theRA procedure based on the first manner, a power lamping counter isinitialized to perform the second RA procedure.
 3. The method of claim1, wherein the information indicating the BWP switching is included indownlink control information (DCI), and the DCI is received from thebase station.
 4. The method of claim 1, wherein the informationindicating the BWP switching is included in a radio resource control(RRC) message, and the RRC message is received from the base station. 5.The method of claim 1, wherein, when information indicating the BWPswitching is received through a RRC message, the RA procedure based onthe first manner is performed among the RA procedure based on the firstmanner and the RA procedure based on the second manner.
 6. The method ofclaim 1, the method further comprising: when a physical random accesschannel (PRACH) resource does not exist in a third BWP, switching fromthe third BWP to the first BWP in which the PRACH resource isconfigured.
 7. The method of claim 6, wherein the first BWP is aninitial uplink BWP.
 8. A terminal, comprising: at least one processor,wherein the at least one processor causes the terminal to: perform afirst random access (RA) procedure with a base station in a firstbandwidth part (BWP); receive information indicating a BWP switchingfrom the base station while the first RA procedure is performed;determine whether the BWP switching is performed; and perform one RAprocedure of a RA procedure based on a first manner and a RA procedurebased on a second manner, based on whether the BWP switching isperformed, wherein, in the RA procedure based on the first manner, theterminal stops the first RA procedure, switches from the first BWP to asecond BWP by performing the BWP switching, and performs a second RAprocedure with the base station in the second BWP, wherein, in the RAprocedure based on the second manner, the terminal ignores an indicationof the BWP switching and continues to perform the first RA procedure inthe first BWP without the BWP switching.
 9. The terminal of claim 8,wherein, in the RA procedure based on the first manner, a power lampingcounter is initialized to perform the second RA procedure.
 10. Theterminal of claim 8, wherein the information indicating the BWPswitching is included in downlink control information (DCI), and the DCIis received from the base station.
 11. The terminal of claim 8, whereinthe information indicating the BWP switching is included in a radioresource control (RRC) message, and the RRC message is received from thebase station.
 12. The terminal of claim 8, wherein, when informationindicating the BWP switching is received through a RRC message, the RAprocedure based on the first manner is performed among the RA procedurebased on the first manner and the RA procedure based on the secondmanner.
 13. The terminal of claim 8, wherein the at least one processorfurther causes the terminal to: when a physical random access channel(PRACH) resource does not exist in a third BWP, switch from the thirdBWP to the first BWP in which the PRACH resource is configured.
 14. Theterminal of claim 13, wherein the first BWP is an initial uplink BWP.